ES22-Adebambo

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

Author: Adebambo, Paul - Federal University of Agriculture, Abeokuta, Nigeria

Title: Assessing the thermoelectric properties of PdScBi half-Heusler alloy

Abstract: We will be discussing the results of our probe into the thermoelectric properties of PdScBi Half-Heusler alloy. This was achieved by combing the density functional theory with Boltzmann transport properties and the modified Callaway model. The results of this finding revealed that PdScBi alloy is dynamically stable. Besides, it was observed that this alloy could be used in thermoelectricity.

Other authors: Ayedun Funmilayo, National Open University of Nigeria, Abuja, Nigeria. Agbaoye Ridwan, Federal College of Dental Technology and Therapy Enugu, Nigeria. Adebayo Gboyega, Federal University of Agriculture, PMB 2240 Abeokuta, Nigeria

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ES22-Adhikary

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Presenter: Adhikary, Souren - Indian Institute of Science Education and Research Tirupati, India

Author: Sasmita Mohakud, Sudipta Dutta and Souren Adhikary. Department of Physics, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati - 517507, Andhra Pradesh, India.

Title: Antiferromagnetic spin ordering in two-dimensional honeycomb lattice of SiP3

Abstract: Magnetism in two-dimension has long been challenging, since the long-range spin-ordering can not sustain the thermal agitation due to vanishing spin-wave excitation gap, as described by Mermin-Wagner theory. Very recently there have been few reports of two-dimensional magnetism in transition metal tri-chalcogenide, halide and boride systems, that arises from uniaxial anisotropy of d-electrons, more specifically due to the spin-orbit-coupling. However, it has still been elusive for purely p-block elements unless introduced through defect engineering in carbon organic frame-works. Here we propose a purely two-dimensional buckled honeycomb-lattice of stoichiometry SiP3 that exhibits antiferromagnetic ground state with itinerant electrons, originating from Fermi-instability as a results of elemental Si substitution in pristine blue phosphorene to downshift the Fermi energy. The diverging density of states at Fermi energy, arising from hybrid bands and subsequent charge transfer from P to Si atoms due to the Lewis base character of P, stabilizes the system in a magnetic ground state. This group-IV - group-V binary system shows antiferromagnetically coupled tiny ferromagnetic triangular domains with magnetism arising from unhybridized π-electrons. Such metal-free and defect-free two-dimensional material can be exploited for spintronic and qubit applications and can tempt further theoretical and experimental explorations.

Antiferromagnetic spin ordering in two-dimensional honeycomb lattice of SiP3

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ES22-Afrassa

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Afrassa, Mesfin Asfaw - Adama Science and Technology University

Title: First principle study on the effect of Mn substitution in NaFeAs

Abstract: This work present the study on the effect of Mn substitution in NaFeAs applying density functional theory(DFT) as implemented in quantum ESPRESSO. In order to investigate this effect, 50% Mn-substitution on Fe site of NaFeAs were done. The band structure and the density of states(DOS) are calculated for non-magnetic (NM) and collinear-magnetic orderings. Comparison was done between NaFeAs and NaFe0.5Mn0.5 As. The calculated band structures indicates that there is a significant change due to Mn in AFM ordering, where the two bands are completely different at the first Γ-point and in between the second Γ-point and the first Z-point. The DOS result shows that the Fe states dominated in the vicinity of the EF , with only a small contribution from the As and Na. Using the DOS value and some approximation for BCS type, the Tc were calculated for NaFeAs and we obtained T c = 9.33k. The DOS in the presence of Mn decreases for AFM ordering and it seems that the effect of Mn on 1111-family is not similar with 111-family of IBSC. The calculated magnetic moment indicated that the material has a Ferii magnetic behavior.

Other authors: Mark Pederson, The University of Texas at El Paso

First principle study on the effect of Mn substitution in NaFeAs

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ES22-Anderson

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Anderson, Tyler - Cornell University

Title: Nonlocal pseudopotentials and time-step errors in diffusion Monte Carlo

Abstract: We present a version of the T-moves approach for treating nonlocal pseudopotentials in diffusion Monte Carlo which has much smaller time-step errors than the existing T-moves approaches, while at the same time preserving desirable features such as the upper-bound property for the energy. In addition, we modify the reweighting factor of the projector used in diffusion Monte Carlo to reduce the time-step error. The latter is applicable not only to pseudopotential calculations but to all-electron calculations as well.

Other authors: Umrigar, Cyrus - Cornell University

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ES22-Asres

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Asres, Georgies A. - Center for Materials Engineering, Addis Ababa Institute of Technology, School of Multi-disciplinary Engineering, Addis Ababa, 1000, Ethiopia

Title: Tuning the electronic structure of Janus WSSe-ZnO heterostructures from first-principles

Abstract: A new class of materials being researched for use in green energy technology is two-dimensional materials with highly adjustable electrical properties. While the photophysical properties of monolayer semiconducting 2D materials have been extensively studied for these applications, van der Waals heterostructures composed of stacks of various types of 2D materials allow for further tuning and optimization of 2D material electronic properties. We investigate the electronic structure of a Janus WSSe vdW heterostructure with a 2D monolayer ZnO using density functional theory computations. To optimize critical properties for photocatalytic and photovoltaic applications, the effects of alignment, strain, and electric field are investigated. We discover that for these applications, in-plane biaxial strain and out-of-plane uniaxial strain allow the band gaps and band edges of this class of heterostructures to be tuned via an interfacial dipole interaction, opening up a new route to band edge tuning of vdW heterostructures.

Other authors: Elizabeth A. Peterson [2][3], Tekalign T. Debela [4], Girma Mekonnen Gomoro [5], Jeffrey B. Neaton [2][6][7]

[2] Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
[3] Liquid Sunlight Alliance, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
[4] Institute for Application of Advanced Materials, Jeonju University, Chonju, Chonbuk 55069, Republic of Korea
[5] Faculty of Engineering and Technology, Mechanical Engineering Department, Assosa University, Assosa, Ethiopia
[6] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA [7] Kavli Energy Nanosciences Institute, Berkeley, CA 94720, USA

Tuning the electronic structure of Janus WSSe-ZnO heterostructures from first-principles

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ES22-Ayoola

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Ayoola, Adeolu - University of Ibadan Nigeria

Title: Formulation of a New Exchange-Correlation Functional for Better Band Gaps in Density Functional Theory

Abstract: In Density Functional Theory formalism, the total energy functional of a system consists of known and unknown parts, the known part consists of kinetic energy of the non-interacting system, the external potential energy and the Hartree or classical coulomb interaction between the electrons. The existence of the unknown part was established by P. Hohenberg and W. Kohn in 1964 and it is known as the Exchange-Correlation Energy which is the major component necessary for accurate prediction of properties of materials.

The true mathematical form of this exchange-correlation Energy is not known, hence, approximations are made for it which reduces the accuracy of DFT, particularly in the case of energy band gaps. In this work, an exchange-correlation potential functional is formulated which is the modification of Hanke and Sham functional in 1998.

The functional was incorporated into the Quantum espresso software package and was used to perform plane-wave based calculation and energy band gaps of some systems were predicted from the formulated functional.

From our functional, we got band gap for Silicon to be 1.10eV which is closer to the experimental value of 1.12eV than that of LDA which is 0.47eV, for Silicon Carbide, experimental value is 2.40eV and we obtained 2.27eV with our functional which is more accurate than 1.35eV from LDA. For Aluminium Phosphate, our method gave 2.28eV while the experimental value is 2.45eV. All these are of error of approximately 6 percent, comparing with the experimental values and LDA results, the exchange-correlation functional in this work has given better predictions of energy band gaps than LDA.

Other authors:
Oyeniyi, Ezekiel. University of Ibadan Nigeria,
O. Akinojo University of Ibadan Nigeria and East African institute for Fundamental Research (EAIFR)

Formulation of a New Exchange-Correlation Functional for Better Band Gaps in Density Functional Theory

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ES22-Balwade

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Balwade, Mahesh -Department of Physics, Indian Institute of Technology, Mumbai, India

Title: Theoretical study of the electronic structure of Sn4Ge using first principles

Abstract: The heavier elements of group-IV provide a fertile ground for new and useful topological quantum materials. A recent theoretical study¹ has predicted two such materials – Ge₅ and Sn₅ having a 5-atom unit cell with space group P-4m2. Taking a cue, we have studied the electronic and magnetic properties Sn₄Ge with similar crystal structure. Our fully relaxed results show that the ground state of Sn₄Ge is stable, metallic and non-magnetic. Not surprisingly, its lattice parameters are somewhat smaller than that of Sn₅ due to the relatively smaller size of Ge atom in comparison to Sn. The inclusion of spin-orbit interaction leads to a significant band-splitting along Γ-M. The Fermi surface plot of one of the bands shows the typical Dirac cone. We also find a strong hybridization between Ge 4p and Sn 5p orbitals in the energy range -4 to -2 eV below the Fermi energy. [1] C. Zhong, Front. Phys. 16(6), 63503 (2021).

Other authors: Singh Prabhakar, Department of Physics, Indian Institute of Technology, Mumbai, India

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ES22-Bonini

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Bonini, John - Flatiron Institute

Title: Chiral phonons from broken time reversal symmetry in CrI3

Abstract: The conventional computational approach to the study of lattice dynamics from first principles is the calculation of forces on nuclei as a function of the set of static nuclei displacements. Within this approach the resulting nuclear equations of motion are, by construction, time-reversal invariant even for systems that break time reversal symmetry in the electronic sector. In this work we develop a first-principles method for computing nuclear equations of motion which capture time reversal broken lattice dynamics. The resulting forces are then not just dependent on nuclei displacements, but also the set of nuclei velocities. These corrected forces result in a splitting of otherwise degenerate phonon frequencies, and phonon eigenvectors which carry angular momentum even in inversion symmetric systems and at the Gamma point. First principles results are presented for CrI3 where splittings of otherwise degenerate phonons are observed.

Other authors: Ren, Shang (Rutgers University); Vanderbilt, David (Rutgers University); Stengel, Massimiliano (ICMAB-CSIC, ICREA); Dreyer, Cyrus (Stony Brook University, Flatiron Institute); Coh, Sinisa (University of California Riverside)

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ES22-Bujdak

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Bujdák, Radovan - Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia

Title: Exploring new phases in Ni-O binary system from ab initio

Abstract: The Ni-O binary system contains only one well known phase, namely NiO, although other stoichiometries such as Ni2O3 and Ni2O5 are perfectly viable but much less studied. Nickel sesquioxide, Ni2O3, also referred to as black nickel oxide is currently being increasingly used as a component for number of functional materials due to its photocatalytic activity [1]. However, the compound remains poorly characterized and its crystal structure, which is a crucial starting point for the understanding of relationship between structure and properties, remains unresolved [2]. On the other hand, nickel pentoxide Ni2O5 represents a completely unknown and unstudied phase. Nevertheless, both sesquioxides and pentoxides are common among other transition metals. For example, majority of 3d transition metals forms sesquioxides and early transition metals such as V, Nb, Ta form pentoxides that exhibit rich polymorphism with various level of structural complexity. Therefore, our study is dedicated to theoretical prediction of crystal structure and structure-related properties of Ni2O3 and Ni2O5 with the use of Density Functional Theory (DFT) and evolutionary algorithms (EA). First, we evaluate the fitness of the structure types commonly observed in sesquioxides and pentoxides of transition metals to accommodate the corresponding Ni oxide by means of DFT calculations. Next, we use DFT modelling in conjunction with EA to search for the global minimum structures [3]. We present the results of thorough spin-polarized DFT calculations (DFT, DFT+U and hybrid DFT) and EA search including crystal, electronic and magnetic structures and lattice dynamics.

Acknowledgement: The European Regional Development Fund, Research and Innovation Operational Programme, for project No. ITMS2014+: 313011W085; Scientific Grant Agency of the Slovak Republic, grant No. VG 1/0223/19; the Slovak Research and Development Agency, grant No. APVV-18-0168; Aurel supercomputing infrastructure in CC of Slovak Academy of Sciences acquired in projects ITMS 26230120002 and 26210120002 funded by ERDF; PRACE FENIX Project fnxp070004 at TGCC high performance computing infrastructure, France.

References:
[1] Shaban, M., Abukhadra, M.R. & Hamd, Clean Techn Environ Policy 20, 13–28 (2018).
[2] P. S. Aggarwal and A. Goswami, National Chemical Laboratory 2-0770 (1961). [3] D. C. Lonie, E. Zurek, Computer Physics Communications 182, 372-387 (2011).

Other authors: Gašpárková, Michaela, Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia; Tokár, Kamil, Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia, Institute of Physics, Slovak Academy of Sciences, 845 11 Bratislava, Slovakia; Derzsi, Mariana, Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia

Exploring new phases in Ni-O binary system from ab initio

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ES22-Chen

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Chen, Siyuan - College of William & Mary

Title: Accurate structural optimizations in solids with auxiliary-field quantum Monte Carlo

Abstract: Structural optimization by accurate, non-perturbative methods has been an outstanding challenge in many-body electronic structure computations. We present the direct computation of forces and stresses in solids by plane-wave auxiliary-field quantum Monte Carlo (AFQMC) [1]. With them, we perform full structural optimizations in several solids [2]. Additionally, we propose a general optimization algorithm, FSSDxSET, for gradients which have intrinsic stochastic noise. This algorithm is found to outperform standard optimization methods and several machine learning algorithms in efficiency and robustness [3].

References:
[1] S. Zhang and H. Krakauer, Phys. Rev. Lett. 90, 136401 (2003); M. Suewattana, W. Purwanto, S. Zhang, H. Krakauer, and E. J. Walter, Phys. Rev. B 75, 245123 (2007)
[2] S. Chen and S. Zhang, in preparation
[3] S. Chen and S. Zhang, arXiv:2204.12074

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ES22-Choudhary

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Choudhary, Kamal - National Institute of Standards and Technology, Gaithersburg, MD, USA

Title: Designing High-Tc Superconductors with BCS-inspired Screening, Density Functional Theory and Deep-learning

Abstract: Recent advances in first principles calculations and machine learning techniques allow for a systematic search for phonon-mediated superconductors. We develop a multi-step workflow for the discovery of conventional superconductors, starting with a Bardeen-Cooper-Schrieffer inspired pre-screening of 1736 materials with high Debye temperature and electronic density of states at the Fermi-level. Next, we perform electron-phonon coupling calculations for 988 of them to establish a large and systematic database of BCS superconducting properties. Using the McMillan-Allen-Dynes formula, we identify 112 dynamically stable materials with transition temperatures, Tc > 5 K. In addition, we analyze trends in our dataset and individual materials including MoN, VC, VTe, KB6, Ru3NbC, V3Pt, ScN, LaN2, RuO2, and TaC. Finally, we demonstrate that deep-learning models can predict superconductor properties, including the Eliashberg function, thousands of times faster than direct first principles computations. We apply the trained model on the crystallographic open database and pre-screen 8293 candidates for further DFT calculations.

Other authors: Garrity, Kevin, National Institute of Standards and Technology, Gaithersburg, Maryland, USA

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ES22-Cogollo

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Cogollo, Beatriz - University of Cartagena

Title: Search for atomic structures by ab initio methods and evolutionary algorithms for monatomic systems under hydrostatic pressure

Abstract: Fluorine has not been as extensively studied compared to other single-element diatomic molecules (H2, N2, O2, Cl2, Br2, I2). In fact, the space group of solid fluorine at ambient pressure has been a source of controversy for many years. Despite multiple spectroscopy studies and theoretical calculations, the discussion regarding the most stable phase of this system at high pressures was still maintained. For this reason, and using computational techniques, only a few years ago, a study established the most stable phase at low pressures and its subsequent transformation to Cmca at 8 gigapascals (GPa). However, recent studies show profound differences between the phases found and their respective transition pressures for much higher pressures.

In this work, structural search calculations were carried out using evolutionary algorithms for pressure ranges in the order of terapascals to establish enthalpy relationships with those post-Cmca phases proposed through less impartial methods.

Other authors: Montoya, Javier - University of Cartagena

Search for atomic structures by ab initio methods and evolutionary algorithms for monatomic systems under hydrostatic pressure

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ES22-Del Grande

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Del Grande, Rafael, University of California, Merced

Title: Excited-state forces in organic metal halide perovskites from GW/BSE calculations

Abstract: Organic metal halide perovskites are promising materials for solar cells and optoelectronic devices, but one of the main barriers to their use is light-induced degradation. Light-induced structural changes also play an important role in Stokes shifts and exciton transport. They have been attributed to mechanisms such as the creation of polaronic trap states from free carriers, halide ion migration, and changes in stress.

To understand those structural changes, we calculate forces induced by absorption of light, with the GW approximation and Bethe-Salpeter equation (GW/BSE). Our excited-state forces method, an improved version of Ismail-Beigi and Louie‚Äôs [Phys. Rev. Lett. 90, 076401 (2003)], combines quasiparticle energies and exciton wavefunctions from GW/BSE calculations in BerkeleyGW with electron-phonon matrix elements from Density Functional Perturbation Theory (DFPT) calculations.

We first benchmark excited-state forces on simple test systems, such as the CO molecule, and then we apply this approach to methylammonium lead iodide perovskite (CH3NH3PbI3), exploring different excitations and crystal phases. Our calculated excited-state forces are the starting point for structural changes induced by light absorption in hybrid perovskites.

Other authors: Strubbe, David. University of California, Merced

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ES22-Edossa

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Edossa, Teshome Gerbaba - Department of Physics, College of Natural and Computational science, Wachemo University, Hosanna, Ethiopia

Title: Study of Electronic, Structural and Optical properties of Cadmium Sulfide (CdS) in Zinc-Blende and Wurtizite phase using DFT and DFT+U

Abstract: Zinc-blende(zb) and wurtzite(wz) structure of CdS was analyzed using DFT within LDA, PBE, GGA+U, and PBE0. To assure the accuracy of calculation, the convergence test of total energy with respect to energy cutoff and k-point sampling is performed. The relaxed atomic position for the CdS in zb and wz structure is obtained by using total energy and force minimization method following the Hellmann Feynman approach. The structural optimization and electronic band structure properties of CdS are investigated. Analysis of the results shows that LDA and PBE underestimate the band-gap due to their poor approximation of exchange-correlation functional. However, the DFT+U and the PBE0 approximation give a good band-gap value which is comparable to the experimental result. Moreover, Optical properties: complex and real parts of dielectric function, static dielectric function, energy-loss spectrum, absorption coefficient and refractive index of CdS in both zb and wz phase were studied within LDA, GGA and DFT + U to characterize its optical nature. Accuracy is found for the calculated values within DFT+U and PBE0 approximation. It is found that the wz-CdS exhibits anisotropy in two directions (in basal plan and z-axis).

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ES22-Eskridge

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Eskridge, Brandon - College of William and Mary

Title: Ab Initio Treatment of Molecular Magnets using Auxiliary-field quantum Monte Carlo (AFQMC)

Abstract: Molecular magnets have seen significant attention due to their potential applications in quantum information / quantum computing. A delicate balance of electron correlation, spin-orbit coupling (SOC), ligand field splitting, and other effects produces a persistent magnetic moment within each molecular magnet unit. The competition among these effects poses a challenge for theoretical treatments. Electron correlation effects play a central role since d-, or f-element ions provide the magnetic states in molecular magnets requiring explicit many-body treatments in general. In addition, the explicit inclusion of SOC expands the dimensionality of the Hilbert space that must be treated. Furthermore, molecular magnets are large systems involving tens of atoms in even the smallest systems. Auxiliary-field quantum Monte Carlo (AFQMC) has demonstrated a high degree of reliability in correlated-electron systems with computational cost that scales as a low order polynomial making applications to large systems feasible. Recent advances in AFQMC technology allow an ab initio treatment in molecular magnets where electron correlation, SOC, and material specificity are included accurately and on an equal footing. We demonstrate the approach by applying AFQMC to compute the zero-field splitting (ZFS) of a linear Co(II) complex.

Other authors: Krakauer, Henry - College of William and Mary; Zhang, Shiwei - Flatiron Institute Center for Computational Quantum Physics

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ES22-Fabusova

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Fabušová, Diana - Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia

Title: Ab Initio Study of Impact of Pressure and Temperature on Stability and Polymorphism of PdO2

Abstract: Palladium is an important catalyst in many catalytic reactions with a diversity of technological applications. Apart from the pure metal, catalytic activity is being increasingly attributed also to palladium oxides, which however remain poorly characterized. The only thoroughly studied and technologically exploited palladium oxide phase is PdO. In our present study we focus on theoretical investigation of crystal structures of PdO2 using Density Functional Theory (DFT) modeling. Formation of only one PdO2 polymorph was reported under elevated hydrostatic pressure and temperature and a rutile structure was proposed [1, 2]. This is contrary to the numerous polymorphs that are known in case of its heavier counterpart PtO2, which suggests that PdO2 should also be stabilized in a variety of structures. In our study, we predict the thermodynamically stable polymorphs of PdO2 at ambient and high pressures within the pressure range 0 ‚Äì 10 GPa and explain the role of pressure and temperature on the stability of rutile type structure using both standard and hybrid DFT functionals [3, 4]. Furthermore, our study demonstrates how the rutile type structure becomes destabilized at low temperatures whereas decompression drives a transition to a new porous structural type that is unknown in case of PtO2.

Acknowledgement: The European Regional Development Fund, Research and Innovation Operational Programme, for project No. ITMS2014+: 313011W085; Scientific Grant Agency of the Slovak Republic, grant No. VG 1/0223/19; the Slovak Research and Development Agency, grant No. APVV-18-0168; Aurel supercomputing infrastructure in CC of Slovak Academy of Sciences acquired in projects ITMS 26230120002 and 26210120002 funded by ERDF; PRACE FENIX Project fnxp070004 at TGCC high performance computing infrastructure, France.

[1] I. S. Shaplygin, G. L. Aparnikov, V. B.Lazarev, Zhurnal Neorganicheskoi Khimii, 23, 884 (1978)
[2] G. I. Goncharenko, V. B. Lazarev, I. S. Shaplygin, Zhurnal Neorganicheskoi Khimii, 30, 3032 (1985)
[3] D. Fabušová°, Bachelor thesis 2020, available at https://opac.crzp.sk/
[4] D. Fabušová°, Master thesis to be defended in June 2020, subsequently available at https://opac.crzp.sk/

Other authors: Tokár Kamil - Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia and Institute of Physics, Slovak Academy of Sciences, 845 11 Bratislava, Slovakia Derzsi Mariana - Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia

Ab Initio Study of Impact of Pressure and Temperature on Stability and Polymorphism of PdO2

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ES22-Ganesh

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Ganesh, Panchapakesan - Center for Nanophase Materials Sciences, Oak Ridge National Laboratory

Title: Harnessing Electron Correlations and Anharmonicity for Energy Efficient Computing

Abstract: Metal oxide-based Resistive Random-Access Memory (RRAM) exhibits multiple resistance states, arising from the activation/deactivation of a conductive filament (CF) formed by oxygen vacancies inside a switching layer – due an underlying metal-insulator transition (MIT). You can make scalable memory/logic units using the crossbar architecture. So, you have a highly dense information-storage system, that you want to be reliable, and fast switching and utilizing low- power. This can enable emulating ‘brain like’ neuromorphic computing. Similarly, ferroelectric materials – such as Hafnia – are promising candidates for synaptic weight elements in neural network hardware because of their nonvolatile multilevel memory effects. But conventional RRAM materials require high forming potentials (not viable in crossbars), show high variability (device-to-device or cycle-to-cycle). Similarly, less reliability and voltage-time dilemma are suspected to plague ferroelectric synapses. To address these challenges, we are working to answer these open questions such as: what material characteristics we need when choosing a memristor material? What factors triggers a state-change (e.g. MIT, magnetic-transition, or ferroelectric-switching) in these materials? What determines the dynamics of the switching mechanism?br />
Using a combination of high-throughput phase-field and machine-learning methods [1] we discovered that harnessing electron-electron correlations in binary oxides can be advantageous for improved performance of RRAM devices. Using a combination of various correlated electronic structure methods, such as Quantum Monte Carlo (QMC) and Dynamical Mean Field Theory (DMFT), we further uncovered the underlying factors that control the MIT in correlated binary oxides – such as VO2 – when defects such as oxygen vacancies are present [2,3]. We subsequently demonstrated how many of the correlated perovskite metals that undergo MIT are negative charge-transfer metals, with the magnitude of ligand-hole being the key to controlling MIT. As such, the underlying mechanism of MIT is similar in such charge-transfer metals, irrespective of whether the MIT is induced by changes in stoichiometry or chemistry or pressure [4]. This work provides a fundamental understanding to resistive switching in RRAM’s. For ferroelectric-based synapses, we explored the recently discovered 2D layered-thiophosphate family of materials [5]. We discovered [6] presence of strong anharmonic coupling in these materials between the polar-mode and a strain-tunable Raman active symmetric-mode, even down to single-layer thickness, which could alleviate the voltage-time dilemma in conventional ferroelectrics. We further show our recent findings of scale-free ferroelectricity in this 2D layered ferroelectric family of materials [7].

[1] High-throughput phase-field simulations and machine learning of resistive switching in resistive random-access memory”, npj Computational Materials volume 6, Article number: 198 (2020), Kena Zhang, Jianjun Wang, Yuhui Huang, Long-Qing Chen, P. Ganesh* & Ye Cao.
[2] Doping a bad metal: Origin of suppression of the metal-insulator transition in nonstoichiometric VO2”, Phys. Rev. B 101, 155129, (2020), P. Ganesh*, Frank Lechermann, Ilkka Kylänpää, Jaron T. Krogel, Paul R. C. Kent, and Olle Heinonen
[3] Metal–insulator transition tuned by oxygen vacancy migration across -TiO2/VO2 interface”, Scientific Reports, 10, 1854 (2020), Qiyang Lu, Changhee Sohn, Guoxiang Hu, XiangGao, Matthew F. Chisholm, Ilkka Kylänpää, JaronT. Krogel, Paul R. C. Kent, Olle Heinonen, P.Ganesh and Ho Nyung Lee

4] Origin of Metal-Insulator Transitions in Correlated Perovskite Metals”, Phys. Rev. Research 4, L022005 (2022), M. Chandler Bennett, Guoxiang Hu, Guangming Wang, Olle Heinonen, Paul R. C. Kent, Jaron T. Krogel, P. Ganesh*.
[5] Tunable quadruple-well ferroelectric van der Waals crystals”, Nature Materials, 19, 43 (2020), John A. Brehm, Sabine M. Neumayer, Lei Tao, Andrew O’Hara, Marius Chyasnavichus, Michael A. Susner, Michael A. McGuire, Sergei V. Kalinin, Stephen Jesse, P. Ganesh, Sokrates T. Pantelides, Petro Maksymovych and Nina Balke
[6] Origin and stabilization of ferrielectricity in CuInP2Se6”, PHYSICAL REVIEW RESEARCH 4, 013094 (2022), Nikhil Sivadas, Peter Doak, P. Ganesh*
[7] Scale Free Ferroelectric Polarization and Responses in 2D Ferroelectrics”, Nikhil Sivadas, Bobby G. Sumpter and P. Ganesh*, (under review)

Video by Panchapakesan Ganesh -

Harnessing Electron Correlations and Anharmonicity for Energy Efficient Computing

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ES22-Gao2

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Presenter: Gao, Siyu - Carnegie Mellon University
Author: Liu, Xingyu & Carnegie Mellon University

Title: Data Driven Discovery of Singlet Fission Materials

Abstract: Singlet fission (SF), the conversion of one singlet exciton into two triplet excitons, could significantly enhance solar cell efficiency. Molecular crystals that undergo SF are scarce. Computational exploration may accelerate the discovery of SF materials. However, many-body perturbation theory (MBPT) calculations of the excitonic properties of molecular crystals are impractical for large-scale materials screening. We use the sure-independence-screening-and-sparsifying-operator (SISSO) machine-learning algorithm to generate computationally efficient models that can predict the MBPT thermodynamic driving force for SF for a dataset of 101 polycyclic aromatic hydrocarbons (PAH101). SISSO generates models by iteratively combining physical primary features. The best models are selected by linear regression with cross validation. The SISSO models successfully predict the SF driving force with errors below 0.2 eV. Based on the cost, accuracy, and classification performance of SISSO models, we propose a hierarchical materials screening workflow. Three potential SF candidates are found in the PAH101 set.

Other authors: Wang, Xiaopeng & Qingdao Institute for Theoretical and Computational Sciences
Gao, Siyu & Carnegie Mellon University Chang, Vincent & Carnegie Mellon University
Tom, Rithwik & Carnegie Mellon University Yu, Maituo & Carnegie Mellon University
Ghiringhelli, Luca & NOMAD Laboratory at the Fritz Haber Institute of the Max Planck Society and Humboldt University

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ES22-Georgescu

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Georgescu, Alexandru Bogdan - Northwestern University, McCormick School of Engineering, Department of Materials Science and Engineering

Title: Machine Learning Assisted Quantum Materials Discovery: Metal-Insulator Transition Compounds

Abstract: Metal–insulator transition (MIT) compounds are materials that may exhibit metallic or insulating behavior, depending on the physical conditions, and are of immense fundamental interest owing to their potential applications in emerging microelectronics. Nonetheless, only around 60 materials with a thermally-driven metal-insulator transition are known, and their computational discovery is difficult due to the non-equilibrium nature of the transition, and the complexity of the many-body problem. To address this issue, we have built the first database of all known thermally-drivem metal-insulator transition compounds, as well as stoichiometrically related compounds, and a machine-learning based classifier tool to accelerate their discovery - and provided both to the wider public, with no installation required. We also present here possible new metal-insulator transition oxide compounds identified through a combination of machine learning and DFT calculations, which may be of interest to the scientific community.

This work was supported in part by the National Science Foundation (NSF) under award number DMR-1729303 and the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0001209.

References: [1] A.B. Georgescu, P. Ren, A.R. Toland, S. Zhang, K.D. Miller, D.W. Apley, E.A. Olivetti, N. Wagner, J.M. Rondinelli, ‘Database, Features, and Machine Learning Model to Identify Thermally-Driven Metal-Insulator Transition Compounds’, Chem. Matter, 2021, 33, 14, 5591-5605 [2] MIT material database: https://mtd.mccormick.northwestern.edu/mit-classification-dataset/ [3] ML Classifier: tinyurl.com/mit-classifiers

Other authors: Rondinelli, James & Northwestern University, McCormick School of Engineering, Department of Materials Science and Engineering

Machine Learning Assisted Quantum Materials Discovery: Metal-Insulator Transition Compounds

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ES22-Haile

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Haile, Asnake - Assosa University

Title: The role of nitrogen and sulfur dual coordination of cobalt in Co-N4−xSx/C single atom catalysts in the oxygen reduction reaction

Abstract: Single-atom catalysts (SACs) have been considered as a potential candidate for fuel cell application due to the fact that they exhibit good oxygen reduction reaction (ORR) activity. In this study, the ORR catalytic activity of sulfur-doped Co-N4/C catalysts, denoted as Co-N4−xSx/C (x = 0–4), is systematically studied via density functional theory calculations. The interaction of the ORR intermediates (*OOH, *O and *OH) with catalysts and the thermodynamics of the ORR process are also taken into account. In addition, electronic structure analysis is employed to investigate the source of the ORR activity, which will help to design promising ORR catalysts with high efficiency at a reasonable price.

Other authors: Heine Anton Hansen, Denmark Technical University, Yedilfana Setarge Mekonnen, Addis Ababa University, and Weldegebriel Yohannes, Addis Ababa University

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ES22-Hurtado

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Hurtado, Adrian - Institute of Advanced Computational Science, Stony Brook University

Title: The fast and accurate calculation of frequency-dependent response properties using a multiresolution adaptive numerical solver at the basis set limit

Abstract: Computing time-dependent molecular properties is an essential task in electronic structure calculations. A computationally efficient method for computing time-dependent response properties is implemented via a time-dependent density matrix formalism. However, calculating frequency-dependent response properties on large, physically relevant systems remains challenging. We present a new multiresolution solver capable of solving the frequency-dependent response equations implemented in our numerical software MADNESS. The solver uses the sparse and adaptive representation of operators in the multiwavelet bases, making possible computing frequency-dependent response properties of large molecules with guaranteed precision and reduced-scaling computational time. To validate our solver, we report preliminary Hartree-Fock frequency-dependent polarizabilities results benchmarked against several Gaussian basis sets.

Other authors:
1. Harrison, Robert, Institute of Advanced Computational Science, Stony Brook University
2. Sekino, Hideo, Institute of Advanced Computational Science, Stony Brook University

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ES22-Jardine

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Jardine, Malcolm - University of Pittsburgh

Title: Electronic structure of the InSb/CdTe/αSn interface: using CdTe as a barrier using DFT

Abstract: The discovery and design of new inorganic interfaces with desirable properties for semiconductor, spintronic, and quantum devices offers a path to new device functionalities. We study the InSb-CdTe-Œ±Sn interface via density functional theory (DFT).¬† InSb is a backbone material of Majorana devices for topological quantum computing and Sn provides the superconductivity that is necessary for inducing Majorana Zero Modes. CdTe is explored tunnel barrier material to help control the coupling between InSb and Sn. The PBE+U method is used, with the Hubbard U parameters found via a machine-learned Bayesian optimization algorithm allowing the simulation of large interfaces. The results of DFT simulations, such as band offsets at the interfaces and the effects of varying the CdTe thickness, will be shown. Namely how many layers of CdTe is needed to act as an effective barrier to electronic effects.

Other authors: Purkayastha, Amrita - U Pitt. Dardzinski, Derek, Yu, Maituo, Marom, Noa - CMU. Chen, A.-H, Hocevar, Moïra - Grenoble Alpes CNRS. Hao, Yu, Palmstrøm, Chris - UC Santa Barbara

Electronic structure of the InSb/CdTe/aSn interface: using CdTe as a barrier using DFT

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ES22-Jayaraj

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Jayaraj, Anooja - Department of Physics, University of North Texas, Denton, TX 76203, USA

Title: Electronic Transport Properties in PAOFLOW 2.0

Abstract: Regardless of its success, the constant relaxation time approximation has limited validity. Temperature and energy dependent effects are important to match experimental trends even in simple situations. We present the implementation of relaxation time approximation models in the calculation of Boltzmann transport in PAOFLOW 2.0 and apply those to model band-structures and thermoelectric materials. In addition, using a self-consistent fitting of the model parameters to experimental conductivity data, we provide a flexible tool to extract scattering rates with high accuracy. We also introduce a method to examine the importance of interband coherence on electronic conductivity and test the validity of the assumption that interband scattering can be ignored in transport.

Other authors: Nardelli, Marco Buongiorno - 1. Department of Physics, University of North Texas, Denton, TX 76203, USA 2. The Santa Fe Institute, Santa Fe, NM 87501, USA Sofo, Jorge O. - 1. Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA 2. Department of Materials Science and Engineering, and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA

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ES22-Jiang

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Jiang, Xuance - Stony Brook University

Title: Uncovering the Structural Characteristics of the Combinatorial Zinc Titanate Thin Film using Multimodal Modeling

Abstract: Zinc titanate is a metal oxide which has promising applications in microwave dielectrics, heterogeneous catalysis, photocatalysis, and energy storage due to its low cost, low toxicity, and good surface properties. However, the properties of the zinc titanate vary on the stoichiometry and different phases in the phase diagram. In order to understand how to control the growth of different phases of zinc titanate, a thin film is grown by combinatorial synthesis method with a monotonically increasing titanium zinc ratio. Multivariate curve resolution (MCR) analysis reveals five phases at different Ti concentration regions, including two known phases - ZnO and TiO2. Three phases remain to be identified that has significant contribution of amorphous structures. We build defect structure models and construct simulated basis for Ti and Zn near edge X-ray absorption spectra. The spectral basis is used to fit the MCR spectral components. By analyzing regression weights on each basis, we identify three phases are comprised of different portion of low energy local motifs in TiZn2O4, TiZnO3, Ti2Zn3O8 compounds and defect structures. We further confirm the low Ti concentration phase as Ti defects in ZnO by analyzing the X-ray diffraction pattern and optical absorption spectra.

Other authors: Li, Ruoshui, Stony Brook University; Zhou, Chenyu, Stony Brook University; Nykypanchuk, Dmytro, Brookhaven National Laboratory; Topsakal, Mehmet, Brookhaven National Laboratory; Hybertsen, Mark, Brookhaven National Laboratory; Stavistki, Eli, Brookhaven National Laboratory; Qu, Xiaohui, Brookhaven National Laboratory; Liu, Mingzhao, Brookhaven National Laboratory; Lu, Deyu, Brookhaven National Laboratory

ES22-Jin

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Jin, Zheting, Yale University

Title: Bond-dependent slave-particle cluster theory based on density matrix expansion

Abstract: Solving large and strongly-correlated electronic problems, exemplified by the Hubbard model on a lattice, is an ongoing electronic structure challenge, and a wide variety of approaches exist in the field. Recent occupation-number based slave-particle methods [1-4] represent a computationally efficient approach for obtaining approximation solutions. In these methods, one decouples the electronic spin and charge degrees of freedom to end up with an easy non-interacting fermion problem on the lattice and an easier interacting auxiliary slave problem on the lattice. However, one must then truncate or simplify the slave problem to render it tractable computationally.

We introduce a new cluster slave-particle method for Hubbard models describing transition metal oxides. The method is based on the expansion of the lattice density matrix into a set of overlapping clusters in real space. Our approach includes all the nearest-neighbor hopping terms directly within the interacting clusters and does not truncate or approximate them at cluster boundaries (unlike prior cluster approaches including cluster DMFT [5-7]). The approach also overcomes some of the shortcomings of prior single-site slave-particle methods (e.g., predicting a false Mott transition in one dimension). We test our approach on 1D and 2D p-d model systems and compare to numerically exact results based on exact diagonalization and density matrix renormalization group (DMRG). We find that our approach is computationally economical and high-quality total energies, site occupancies and d-site double occupancies as a function of Coulomb interaction strength and doping.

References
[1] S. Florens and A. Georges, Phys. Rev. B 70, 035114 (2004)
[2] L. de‚ÄôMedici, A. Georges, and S. Bierman, Phys. Rev. B 72, 205124 (2005)
[3] B. Lau and A. Millis, Phys. Rev. Letter 110, 126404 (2013)
[4] A. Georgescu and S. Ismail-Beigi, Phys. Rev. B 92, 235117 (2015)
[5] S. Hassan and L. de‚ÄôMedici, Phys. Rev. B 81, 035106 (2010)
[6] E. Zhao and A. Paramekanti, Phys. Rev. B 76, 195101 (2007)
[7] M. Hettler et al., Phys. Rev. B 58, 7475 (1998)

Other authors: Ismail-Beigi, Sohrab, Yale University

Bond-dependent slave-particle cluster theory based on density matrix expansion

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ES22-Karmakar

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Karmakar, Sreejani - Department of Physics, Indian Institute of Science Education and Research, Tirupati

Title: Hybrid DFT Based Prediction of a New Photocatalyst: g − B3C2N3

Abstract: Computational designing and screening of two dimensional materials to find efficient and stable photocatalyst is extremely important, in order to achieve green hydrogen fuel based economy. Here, using hybrid density functional theory (DFT) based calculation, a new two-dimensional (2D) B-C-N material, g−B3C2N3 is proposed to have promising prospect in metal-free photocatalysis. It is a direct band gap (3.69 eV), near UV absorbing semiconductor with robust dynamical and mechanical stability. The band positions with respect to water oxidation and hydrogen reduction potential levels, shows that g − B3C2N3 monolayer has the ability to be used for hydrogen fuel generation through spontaneous solar water splitting, over a broad pH range. To improve on the photon harvest efficiency and optimize the band alignment even further, the opto-electronic properties are modulated through biaxial strain application. Tensile strain application provides balanced HER-OER offsets with red shifted absorption spectra, implying higher photon harvest under solar irradiation. Moreover, the condition of pH and/or strain, g − B3C2N3 can be used as a key to control the redox offset and perform various photocatalytic reactions or suppress side reactions selectively, as per requirement. This may address many sustainable goals e.g. green energy production, carbon sequestration, waste water purification and beyond.

Other authors: Adhikary, Souren - Department of Physics, Indian Institute of Science Education and Research, Tirupati; Dutta, Sudipta - Department of Physics and Center for Atomic, Molecular and Optical Sciences - Technologies, Indian Institute of Science Education and Research, Tirupati

Hybrid DFT Based Prediction of a New Photocatalyst: g − B3C2N3

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ES22-Kim

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Kim, Yong-Hoon - Korea Advanced Institute of Science and Technology (KAIST), Korea

Title: Introducing Multi-Space DFT for Nonequilibrium Quantum Transport Calculations

Abstract: Abstract: In the effort to develop novel functional materials and advanced devices based on them, first-principles or ab initio simulations are playing an increasingly important role by providing atomistic information that are not easily accessible in experiments. In this respect, a key ingredient that is still immature and should be further developed is the capability to treat non-equilibrium open junction systems under finite bias in a first-principles manner. For example, for graphene electrode-based van der Waals 2D tunneling transistors, ab initio simulations are currently not possible due to the inherent limitations of the standard approach combining density functional theory (DFT) and non-equilibrium Green‚Äôs function (NEGF) formalisms [1-2]. In this presentation, I will discuss the formulation and applications of the multi-space constrained-search DFT (MS-DFT) formalism we have been developing at KAIST for the past decade plus [1-4]. Seeking an alternative to the standard Landauer picture for quantum transport, we first propose a viewpoint that maps quantum transport processes to space-resolved (drain-to-source) optical excitation counterparts. The multi-space excitation picture for quantum transport then allows the formulation of microcanonical approaches for quantum transport, and the resulting MS-DFT provides unique opportunities in understanding and designing nanoscale devices in operando conditions. For example, unlike in the grand-canonical DFT-NEGF, the non-equilibrium total energy as well as quasi-Fermi level or voltage drop profile information can be obtained within the microcanonical MS-DFT [3,4]. As an appropriate thermodynamic potential for biased electrode/channel interfaces, I then establish the concept of electric enthalpy of formation. Key initial results obtained for electrified water/electrode interfaces will be outlined [5].

[1] H. S. Kim & Kim, Y.-H. ‚ÄúConstrained-search density functional study of quantum transport in two-dimensional vertical heterostructures‚Äù, arXiv:1808.03608 [cond-mat.mes-hall] (2018).
[2] T. H. Kim, J. Lee, R. Lee, & Y.-H. Kim, ‚ÄúGate-versus defect-induced voltage drop and negative differential resistance in vertical graphene heterostructures‚Äù. Npj Comput. Mater. 8, 50 (2022).
[3] J. Lee, H. S. Kim, and Y.-H. Kim, "Multi-space excitation as an alternative to the Landauer picture for non-equilibrium quantum transport", Adv. Sci. 7, 2001038 (2020).
[4] J. Lee, H. Yeo, and Y.-H. Kim, "Quasi-Fermi level splitting in nanoscale junctions from ab initio", Proc. Natl. Acad. Sci. U. S. A. 117, 10142 (2020)
[5] J. Lee and Y.-H. Kim, ‚ÄúFirst-principles study of the hydrogen-bonding network in water at the biased electrode interface‚Äù, Bull. Amer. Phys. Soc. 65, F45.00006 (2020)

Multi-space DFT study of quantum transport in vertical van der Waals 2D transistors

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ES22-Lisesivdin

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Presenter: Lisesivdin, Sefer Bora - Gazi University

Author: Sarikavak-Lisesivdin, Beyza - Gazi University

Title: gpaw-tools: UI/GUI scripts for GPAW software

Abstract: GPAW is a density functional theory (DFT) code based on the Projector Augmented Wave (PAW) method written primarily in Python. It has high integration with ASE (Atomic Simulation Environment) software and Python language. However, this high level of integrity requires knowledge of the Python language and therefore limits the number of GPAW users worldwide. In this study, we are reporting a free cross-platform Python scripts called gpaw-tools for an end user who is not interested in the Python language itself and is interested in pure materials science. The aim of gpaw-tools scripts are to offer user interface (UI) and Tcl/Tk based graphics user interface (GUI) software. With gpaw-tools, the end user can calculate, view and save the elastic properties, state of density (DOS), partial DOS (PDOS), band structure, charge densities and optical properties (both RPA and BSE) of the studied structure without knowledge of Python language. The gpaw-tools scripts are free software and distributed with MIT license.

gpaw-tools: UI/GUI scripts for GPAW software

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ES22-Lopez-Morales

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: López-Morales, Gabriel I.
a. Department of Physics, City College of the City University of New York, New York, NY;
b. Department of Chemistry, Lehman College of the City University of New York, Bronx, NY;
c. The Graduate Center of the City University of New York, New York, NY

Title: Density functional theory and quantum embedding studies of Er3+ in WS2

Abstract: Single photon emitters in the form of rare-earth (RE) impurities are being actively explored as solid-state spin-qubits, largely due to their electronically screened 4f states that result in hours-long coherence lifetimes and, as in the case of Er3+, homogeneous linewidths as narrow as 50 Hz within the telecom band. Harnessing the intrinsic potential of Er3+ and other REs, however, relies on finding suitable host materials that avoid unwanted decoherences in the form of strain and/or hyperfine interactions, while being easily integrated with current device technology. An interesting alternative along these lines is monolayer tungsten disulfide (WS2), a low spin-active nuclei transition metal dichalcogenide (TMD) with a bandgap of ~2.1 eV and sizable lattice constant, that is easily integrated into nanoscale devices. Motivated by these considerations, we employ computational methods to study a substitutional Er3+ impurity (ErW) in monolayer tungsten disulfide (WS2). We start by using density functional theory (DFT) to predict its ground state atomic structure along with charge-state stabilities, while identifying potential electronic transitions via linear response theory within DFT. Strong correlations, however, prevent DFT from quantitatively describing the emerging many-body states and excitations within the 4f manifold, while the required defect supercell sizes render many-body methods inapplicable. As an attempt to overcome such limitations, we consider a quantum embedding method, recently applied to similar point-defect systems. The method is based on the constrained random phase approximation (cRPA) and a localized basis via Wannierization to construct an effective Hamiltonian that describes a subspace containing only the relevant defect states. By treating the 4f manifold of an isolated Er3+ as our correlated subspace, and benchmarking against quantum chemistry methods via the full-configuration interaction (FCI), we plan to characterize and incorporate further terms (such as spin-orbit coupling) into the effective Hamiltonian for the isolated Er3+ and extend it to the case of ErW in WS2. Such an approach could potentially describe the many-body states and 4f–4f excitations more quantitatively, with the possibility of being extended to other RE dopants in similar host matrices.

Other authors: Hampel, Alexander; d. Menon, Vinod M.; a.c. López, Gustavo E.; b.c. Dreyer, Cyrus; d.e Flick, Johannes; d. Meriles, Carlos A.
a. Department of Physics, City College of the City University of New York, New York, NY 10031, USA;
b.Department of Chemistry, Lehman College of the City University of New York, Bronx, NY 10468, USA;
c.The Graduate Center of the City University of New York, New York, NY

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ES22-Luo

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Luo, Chenxing - Applied Physics and Applied Mathematics Department, Columbia University

Title: Ab initio calculation of third-order elastic constants

Abstract: To describe elastic wave propagation in a medium under stress or strain, the second-order elastic constants (SOEC) need to be modified. Early studies have shown this can be accomplished by introducing additional third-order elastic constants (TOEC) [1]. In this study, we reevaluate these accommodations theoretically and provide ab initio verifications. We first examine the effect of hydrostatic stress, i.e., we describe the pressure derivative of SOEC; then, as a more general case, we investigate the modifications needed for the SOEC under hydrostatic and deviatoric stress. We show that in both cases the modifications of the SOEC are linear combinations of SOEC and TOEC. The relationships are tested on NaCl and MgO with ab initio calculated SOEC and TOEC vs. pressure. The methods to compute finite-pressure TOEC are also self-consistently tested.

[1] R. N. Thurston, K. Brugger, Phys. Rev. 133, A1604–A1610 (1964).

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ES22-Magero

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Magero, Denis - Alupe University College, Department of Chemistry and Biochemistry, Kenya

Title: Test of the Orbital-Based LI3 Index as a Predictor of the Height of the 3MLCT → 3MC Transition-State Barrier for Gas-Phase [Ru(N∧N)3]2+ Polypyridine Complexes

Abstract: This work concerns the luminescence lifetimes of Ru(II) polypyridine complexes such as the much studied tris(2,2’ bipyridine)ruthenium(II) ion. The present work is part of the continuation of previous work aimed at clarifying factors responsible for long luminescence lifetimes which has already resulted in two publications [1, 2]. These two publications sought to find ligand field theory (LFT) like luminescence indices which correlated with experimental high luminescence lifetimes. A more direct evaluation of the luminescence indices involves calculating the height of the transition state barrier (or barriers) on the lowest triplet state potential energy surface of these complexes. It is the goal of the present study to calculate these barriers for at least several of these complexes to compare against the previously developed luminescence indices.

Other authors: CASIDA Mark, Universite Grenoble Alpes, France, DARGHOURTH Aladin Ali, University of Mosul, Iraq, SHARMA Sandeep, University of Colorado, USA

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ES22-Mandal

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Mandal, Subhasish - Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA

Title: Building a beyond-DFT database of spectral functions for correlated materials

Abstract: Generating databases of the electronic structure of materials is a key to data-science-driven materials discovery. Many existing materials databases, which were constructed in the spirit of the Materials Genome Initiative, rely almost exclusively upon DFT engines and often make incorrect predictions for many correlated materials. Because qualitative predictions of excited-state properties usually require beyond-DFT methods, various advance methods such as meta-GGAs, hybrid functionals, GW, and dynamical mean-field theory (DMFT) have been developed to describe the electronic structure of correlated materials. However, the expected accuracy of these methods when applied to various classes of materials remains unclear. It is thus of pressing interest to compare their accuracy for different types of materials, and at the same time, to build a broad publicly-available database of the results of beyond-DFT calculations [1]. Here we highlight some of the challenges involved in generating such a beyond-DFT database using high-throughput computations, and show how we have overcome these challenges in our systematic study of these methods on various training sets of moderately and strongly correlated materials.

1. https://jarvis.nist.gov/jarvisbdft/; S. Mandal et al. npj. Comput. Mater. 5, 115 (2019); arXiv:2101.03262 (2021)

Acknowledgment: This research was supported by NSF DMREF DMR-1629059, ONR N00014-20-1-2107, and the Simons Foundation via the Simons Collaboration on the Many Electron Problem

Other authors: Haule, Kristjan; Rabe, Karin; Vanderbilt, David; Department of Physics and Astronomy, Rutgers University, Piscataway, NJ,

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ES22-Mekonnen

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Mekonnen, Yedilfana - Addis Ababa University

Title: Theoretical Studies of Charge Transport in Rechargeable Batteries: Lithium-ion and Metal-air Batteries

Abstract: Today, most electric vehicles and hybrid electric vehicles rely on Li-ion batteries. The main drawbacks of Li-ion batteries are their high price, slow charging, and low energy/power density compared with that gasoline. The (001) Li2MSiO4 surface ionic diffusion studies revealed unlimited and fast ionic diffusion in all three dimensions with over 12-orders-of- magnitude compared with the bulk system. In the past two decades, significant efforts have been paid to the development of next-generation battery technologies. In particular, metal−air batteries (e.g., Li−, Na−, Mg−, Al− and Zn−O2 batteries) are promising and have gained significant attention, especially in the making of economical and efficient products in the transport sector. However, there are several shortcomings that hinder the practicality of metal-air batteries such as poor conductivity and rechargeability, dendrite formation, air contamination (water vapor and CO2 contamination), and stability of electrodes and electrolytes. Our theoretical results disclosed that despite the insulating nature of these discharge products and the cathode-electrolyte interfaces, the Li+ and Na+ -ions diffusion takes place at a high rate with an energy barrier of less than 0.5 eV. Moreover, results revealed that CO2 contamination significantly affects the capacity and overpotentials in Li- and Na-O2 batteries, the significant effect already observed at 1% CO2 due to carbonate formation. Charge transport studies showed that surfaces and interfaces offer an improved conductivity.

References:
1. Journal of Materials Chemistry A, 2022, DOI: 10.1039/D1TA10933B
2. RSC Advances, 2021, 11, 9721, DOI: 10.1039/d1ra00642h
3. J. of Chem. Phys., 2020,152(8), 74711, DOI: 10.1063/1.5141931
4. RSC Advances, 2020,10(36), 21387–21398, DOI: 10.1039/d0ra03126g
5. The J. Phy.Chem. Letters, 2018, 9(15), 4413-4419, DOI: 10.1021/acs.jpclett.8b01790
6. J. of Phy. Chem. C, 2015, 119, 32, 18066-18073, DOI: 10.1021/acs.jpcc.5b04432
7. J. Chem. Phys. 2014, 140, 121101, DOI: 10.1063/1.4869212

Other authors: Sakata, Gamachis; Benti, Nate; Kebele, Negash; Tiruye, Girum; Geffe, Chernet; Mustefa, Ahmed

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ES22-Meng

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Meng, Fanchen - Brookhaven National Laboratory

Title: Multi-code Benchmark on Ti K-edge X-ray Absorption Spectra of Ti-O Compounds

Abstract: X-ray absorption spectroscopy (XAS) is an element-specific characterization technique that is sensitive to a material's structure and electronic properties. First-principles XAS simulations have been widely used as to interpret spectra and draw physical insights. Recently, there has also been a growing interest in building computational XAS databases to enable machine learning applications. While several codes are widely used to calculate XAS, non-trivial differences exist both in their underlying formalism and implementation. A systematic comparison between these codes is crucial for assessing reliability and reproducibility of computational XAS data.

In this work, we benchmark Ti K-edge XAS simulations of Ti-O binary compounds using three state-of-the-art codes: XSPECTRA, OCEAN, and EXCITING. We study their convergence behavior with respect to input parameters and present a workflow to automate and standardize inputs to ensure reliable spectra. This allows us to quantitatively compare the results from the three codes and understand the effects due to differences in their treatment of the electron--core-hole interaction.

Other authors: Vinson, John - National Institute of Standards and Tech; Selcuk, Senser - Brookhaven National Laboratory; Hybertsen, Mark - Brookhaven National Laboratory; Maurer Benedikt & Humboldt University of Berlin; Vorwerk, Christian - University of Chicago; Draxl, Claudia - Humboldt University of Berlin; Qu, Xiaohui - Brookhaven National Laboratory; Lu, Deyu - Brookhaven National Laboratory

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ES22-Mihm

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Mihm, Tina N - Chemistry, University of Iowa

Title: Using the transition structure factor to reach the thermodynamic limit faster in periodic coupled cluster theory

Abstract: Given the large role metals play in applications like catalysis and surface chemistry, there is a current need for efficient calculations using high-accuracy wavefunction-based methods. For method like coupled cluster, however, these calculations are expensive to run due to the large finite size errors associated with simulating a metal with a periodic finite supercell. Here I will present on our twist angle selection method called “structure factor twist averaging” that we developed to help address this cost. Typically, twist angles are used to change the occupation of orbitals, which breaks degeneracy and produces a different energy at each new twist angle. Averaging over a set of twist angles can reduce finite size error and produces a more balanced description of the system but is expensive to run. Our method uses a property of the solids called the transition structure factor to select the one twist angle that reproduces the average system and contains the smallest amount of finite size errors. Given the direct relationship the transition structure factor has with the energy, we find that it is an effective way to select our special twist angle. I will demonstrate the effectiveness of this method for a range of system sizes and basis sets using a model system. I will also show how our method performs with real systems by applying it to a range of solids.

Other authors:
Schäfer, Tobias (Institute for Theoretical Physics, TU Wien, Vienna, Austria),
Weiler, Laura (Chemistry, University of Iowa, Iowa City, IA),
Ramadugu, Sai Kumar (Chemistry, University of Iowa, Iowa City, IA),
Grüneis, Andreas (Institute for Theoretical Physics, TU Wien, Vienna, Austria),
Shepherd, James J. (Chemistry, University of Iowa, Iowa City, IA)

Using the transition structure factor to reach the thermodynamic limit faster in periodic coupled cluster theory

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ES22-Moayedpour

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Moayedpour, Saeed - Carnegie Mellon University

Title: Structure prediction of epitaxial inorganic interfaces by lattice and surface matching with Ogre

Abstract: We present a new version of the Ogre open source Python package with the capability to perform structure prediction of epitaxial inorganic interfaces by lattice and surface matching. In the lattice matching step, a scan over combinations of substrate and film Miller indices is performed to identify the domain-matched interfaces with the lowest mismatch. Subsequently, surface matching is conducted by Bayesian optimization to find the optimal interfacial distance and in-plane registry between the substrate and the film. For the objective function, a geometric score function is proposed based on the overlap and empty space between atomic spheres at the interface. The score function reproduces the results of density functional theory (DFT) at a fraction of the computational cost. The optimized interfaces are pre-ranked using a score function based on the similarity of the atomic environment at the interface to the bulk environment. Final ranking of the top candidate structures is performed with DFT. Ogre streamlines DFT calculations of interface energies and electronic properties by automating the construction of interface models. The application of Ogre is demonstrated for two interfaces of interest for quantum computing and spintronics, Al/InAs and Fe/InSb.

Other authors: Dardzinski, Derek ; Yang, Shuyang , Hwang, Andrea , and Marom, Noa

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ES22-Modine

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Modine, N.A., Sandia National Laboratories, Albuquerque, New Mexico

Title: A machine learning surrogate for density functional theory based on the local density of states

Abstract: We present a workflow based on machine learning (ML) that can reproduce Kohn-Sham density functional theory (DFT) total energies to within chemical accuracy (< 1 kcal/mol) with a computational cost that scales linearly with system size. This workflow uses a deep neural network to predict the local density of states (LDOS) as a function of the nearby arrangement of atoms, which is encoded using spectral neighbor analysis potential (SNAP) descriptors. From the LDOS, spatially-resolved, energy-resolved, and integrated quantities can be calculated, including the DFT total energy and forces, and we will discuss implementation of these calculations. Once the ML model has been trained on the LDOS for cells where DFT calculations are practical, the model can be accurately and efficiently applied to much larger systems. Compared to DFT, the only new approximation in this approach is the determination of the LDOS using a local ML model rather than by solving the Kohn-Sham equations. In particular, the treatment of charge transfer through the determination of a global Fermi level and the incorporation of long-ranged electrostatic contributions to the energy are exactly the same as DFT. We will propose application of this approach to several problems that are very challenging for conventional interatomic potentials including: (1) charged defects in semiconductors and insulators, (2) systems where the effects of electronic temperature need to be represented, and (3) metal-insulator transitions induced by structural changes.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. DOE's National Nuclear Security Administration under contract DE-NA0003525. The Center for Advanced Systems Understanding (CASUS) is financed by the German Federal Ministry of Education and Research (BMBF) and by the Saxon Ministry for Science, Art, and Tourism (SMWK) with tax funds on the basis of the budget approved by the Saxon State Parliament.

Other authors: Fiedler, Lenz 2,3; Vogel, D.J. 1; Thompson, A.P. 1; Ellis, J.A. 4, Stephens, J.A., Popoola, G.A., Cangi, Attila 2,3, and Rajamanickam, S. 1 1 Sandia National Laboratories, Albuquerque, New Mexico 87185, USA 2 Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany 3 Helmholtz-Zentrum Dresden-Rossendorf, D-01328 Dresden, Germany 4 Oak Ridge National Laboratory, Oak Ridge, Tennessee 27830, USA

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ES22-Mukherjee

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Mukherjee, Arpita - SRM Institute of Science and Technology

Title: A First Principle study on structural, electronic and magnetic properties of bilayer T-VSe2(001)/Co heterostructureA First Principle study on structural, electronic and magnetic properties of bilayer T-VSe2(001)/Co heterostructure

Abstract: Over the last few years, researchers have been interested in studying the various properties of transition metal dichalcogenides(TMDs). Layered TMDs consist of one TM bonded with two chalcogen atoms forming covalent bond. Vanadium diselenide(VSe2) is a typical example whose bulk is paramagnetic and surprisingly its monolayer seems to be ferromagnetic. In bulk VSe2, Se-V-Se layers are stacked along (001) direction forming trigonal(T) phase crystal[1]. Hence, these 2D structures can reveal distinctive properties compared to that of the bulk counterparts. Here we propose a completely new heterostructure based on VSe2 on cobalt substrate. The properties were studied using DFT and DFT+U approach considering the vanderwaals correction between the layers. Results reveal the antiferromagnetic coupling between VSe2 and Co, thereby reducing the magnetic moment of Co atom. This is a direct consequence of the presence of Co-V hybridization across the interface, which is consistent with the previous result[2]. Bader charge analysis showed a charge transfer between V and Co via Se atom. These findings opens up new path for tuning the electronic properties of VSe2 based nanostructures. Keywords :- TMDs, VSe2, trigonal phase, electronic, hybridization, antiferromagnetic coupling

References :
1.Bayard, M.; Sienko, M. J. Anomalous Electrical and Magnetic Properties of Vanadium Diselenide. J. Solid State Chem. 1976, 19, 325−329.
2.Wen Zhang, Lei Zhang, Ping Kwan Johnny Wong, Jiaren Yuan, Giovanni Vinai, Piero Torelli, Gerrit van der Laan, Yuan Ping Feng, and Andrew T. S. Wee. Magnetic Transition in Monolayer VSe2 via Interface Hybridization. ACS Nano. 2019, 13(8), 8997-9004.

Other authors: Rana Tushar & SRM Institute of Science and Technology

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ES22-Nkala

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Nkala, Gugulethu C.
1. Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag X3, Johannesburg, 2050, South Africa, 2. DSI-NRF Centre of Excellence in Strong Materials, Private Bag X3, Johannesburg, 2050, South Africa

Title: On the average, local and electronic structure of NASICON-type Li1.3Al0.25Dy0.05Ti1.7(PO4)3 (LADTP)

Abstract: Understanding structure-property correlations in materials of technological importance has been the driving force in investigating NASICON-type LiTi2(PO4)3 (LTP) systems as potential solid-state electrolytes for Li-ion batteries. Variously substituted LTP systems have been extensively investigated to increase Li+ ion conductivity in the NASICON-type structures, more specifically, the co-doped systems wherein the Ti4+ is substituted by aliovalent M3+ ions.1-3 In these studies, both strategies of enhancing Li+ ion conductivity, viz. tuning the bottleneck size by enlarging the M3+/4+O6 octahedra, and increasing the charge carrier concentration, have been employed. This is done by substituting Ti4+with a simultaneously larger and aliovalent cation at the 12c site of the rhombohedral LTP (space group R-3c). In this work, a new co-doped system, Li1.3Al0.25Dy0.05Ti1.7(PO4)3 (LADTP) is investigated. We study the average structure via synchrotron XRD and laboratory-based Raman spectroscopy, which suggest a predominantly rhombohedral (R-3c) phase. By applying small-box modelling on the pair distribution function (PDF) data, a monoclinic (P21/c) local structure up to 10 Å, showing a deviation from the average rhombohedral structure is reported for the first time. A combination of experimental and theoretical XANES supports the presence of Dy dopants in the monoclinic arrangement in the structure, in combination with a Dy3+-bearing phosphate secondary phase formed due to the ionic radii difference between Ti4+ and Dy3+. These results provide an understanding of the local and average structure that govern ionic conductivity which may facilitate further improvements on existing materials for solid-state electrolyte applications.

References 1. Nikodimos, Y., Tsai, M.C., Abrha, L.H., Weldeyohannis, H.H., Chiu, S.F., Bezabh, H.K., Shitaw, K.N., Fenta, F.W., Wu, S.H., Su, W.N. and Yang, C.C., 2020. Al–Sc dual-doped LiGe2(PO4)3–a NASICON-type solid electrolyte with improved ionic conductivity. Journal of Materials Chemistry A, 8(22), pp.11302-11313. 2. Zhang, P., Wang, H., Si, Q., Matsui, M., Takeda, Y., Yamamoto, O. and Imanishi, N., 2015. High lithium ion conductivity solid electrolyte of chromium and aluminum co-doped NASICON-type LiTi2(PO4)3. Solid State Ionics, 272, pp.101-106. 3. Kothari, D.H. and Kanchan, D.K., 2015. Study of Study of electrical properties of gallium-doped lithium titanium aluminum phosphate compounds. Ionics, 21(5), pp.1253-1259.

Other authors; Masina, Sikhumbuzo M., Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag X3, Johannesburg, 2050, South Africa Vila, Fernando D., Department of Physics, University of Washington, Seattle, WA, United States Rehr, John R., Department of Physics, University of Washington, Seattle, WA, United States Erasmus, Rudolph M., Materials Physics Research Institute, School of Physics, University of the Witwatersrand, Private Bag X3, Johannesburg, 2050, South Africa Forbes, Roy P., Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag X3, Johannesburg, 2050, South Africa Billing, Caren, Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag X3, Johannesburg, 2050, South Africa Billing, David G., 1. Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag X3, Johannesburg, 2050, South Africa, 2. DSI-NRF Centre of Excellence in Strong Materials, Private Bag X3, Johannesburg, 2050, South Africa

On the average, local and electronic structure of NASICON-type Li1.3Al0.25Dy0.05Ti1.7(PO4)3 (LADTP)

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ES22-Oshakuade

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Oshakuade, Olugbenga - Department of Physics, University of Ibadan, Ibadan, Nigeria

Title: Effects of pressure on the electronic properties of KSnX3 (X=Cl,Br,I) perovskites

Abstract: The power conversion efficiency of solar cells is known to be highly dependent on the band gap of photovoltaic materials. Hence, tuning the band gap to the appropriate band gap range for solar cells is one fundamental method to improve the power conversion efficiency of solar cells. In this work, the electronic bandstructure of KSnCl3, KSnBr3 and KSnI3 have been calculated using plane wave-based DFT method. The solution of the Murnaghan equation was obtained by fitting optimal cell volume, bulk modulus and the derivative of bulk modulus to predict calculated total energies at different lattice constants. All the systems were found to be semiconducting within the pressure considered except for KSnI3 that exhibited metallic behavior at 40 GPa. The band gap was found to decrease with pressure. The systems, under pressure, can absorb in the visible region, making them potential materials for solar cell and optoelectronic applications.

Other authors: Oyeniyi, Ezekiel. Department of Physics, University of Ibadan, Ibadan, Nigeria

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ES22-Ovčar

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Ovčar, Juraj - Ruđer Bošković Institute, Zagreb, Croatia

Title: An Insight into Halide Ordering in Mixed-Halide 2D Perovskites via Global Structure Optimization

Abstract: Hybrid quasi-two-dimensional perovskites (Q2DPs) are a class of materials consisting of lead-halide perovskite slabs intercalated with (bi)layers of organic cations. This pronounced anisotropy leads to quantum and dielectric confinement of the charge carriers to the quasi-2D perovskite layers, giving rise to widely tunable physical properties beneficial for optoelectronic and photovoltaic applications. The tunability of the physical properties stems from the great variety of possibilities in choosing the particular chemical composition of the material. This poster presents a computational method, dubbed GO-MHALP (Global Optimization by Minima Hopping Algorithm for Layered Perovskites), which intends to predict the crystal structure of Q2DPs for a given chemical composition utilizing a combined classical potential & DFT approach. We use GO-MHALP in a joint experimental and computational investigation to show that mixing iodine and bromide halides allows for synthesis of a Q2DP with the bulky tert-butyl ammonium cation.

Other authors: Lončarić, Ivor; Grisanti, Luca; Mladineo, Bruno; Popović Jasminka (Ruđer Bošković Institute, Zagreb, Croatia); Djurišić, Aleksandra (The University of Hong Kong, Hong Kong)

An Insight into Halide Ordering in Mixed-Halide 2D Perovskites via Global Structure Optimization

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ES22-Petras

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Petras, Hayley R. - University of Iowa

Title: Diatomic potential energy surfaces and the effect of temperature

Abstract: We present data showing the effect of finite electronic temperature on the potential energy surfaces of first row homodiatomic molecules. Our approach is to use finite temperature full configuration interaction to first evaluate how the surfaces change with temperature. We will show temperature dependent surfaces for lithium, beryllium, boron, carbon, oxygen and fluorine all in the STO-3G basis set. We find that each diatomic exhibits a set of a qualitative features that are similar across the first row diatomics. In addition, we explore how strong correlation changes with temperature in N2/cc-pVDZ by analyzing the particle population on the density matrix throughout the piecewise interaction picture density matrix quantum Monte Carlo (PIP-DMQMC) simulations. Finally, we will analyze how the strength of the bond changes with temperature by fitting the temperature dependent surfaces to a Harmonic Oscillator model, and calculating the associated force constants for all the diatomics.

Other authors: Van Benschoten, William Z. (University of Iowa); Shepherd, James J. (University of Iowa)

Diatomic potential energy surfaces and the effect of temperature

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ES22-Ping

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Ping, Yuan - University of California, Santa Cruz

Title: First-Principles Many-Body Theory and Quantum Dynamics for Materials in Quantum Information Science

Abstract: Stable, scalable, and reliable quantum information science (QIS) is poised to revolutionize human well-being through quantum computation, communication and sensing. Here, I show our recent development on first-principles computational platforms to study quantum coherence and optical readout as critical processes in QIS in solid-state materials, by combining first-principles many-body theory and open quantum dynamics. First, we show how we reliably predict energetics, electronic and optical properties of spin defects and their host two-dimensional(2D) materials from first-principles many-body theory, which accurately describes highly anisotropic dielectric screening and strong many-body interactions. In particular, we show how we identify the chemical composition of single photon emitters in hexagonal boron nitride and 2D magnet NiPS3 by computing optical transitions, radiative and nonradiative as well as intersystem crossing kinetic rates with strong exciton-defect couplings from first-principles. Next, we introduce our recently developed real-time density-matrix dynamics approach with first-principles electron-electron, electron-phonon, electron-impurity scatterings and self-consistent spin-orbit coupling, which can accurately predict spin and carrier lifetime and pump-probe Kerr-rotation signatures for general solids. As an example, we will show our theoretical prediction on Dirac materials under electric field with extremely long spin lifetime and spin diffusion length and spin relaxation in bulk halide perovskite. This theoretical and computational development is critical for designing new materials promising in quantum-information science, spintronics, and valleytronics applications.

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ES22-Popoola

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Popoola, Adewumi - Department of Physics, Federal University of Technology Akure, Nigeria

Title: The Effect of Chromium in Ytterbium Monoxide towards Spintronics Application

Abstract: The Density Functional Theory (DFT) calculation method have been used to investigate the structural properties, electronic structures, and the magnetic properties in ytterbium monoxide (YbO) induced with chromium (Cr) in the stoichiometry Yb1-xCrxO (0.25 ≤ x ≥ 0.75). The dynamic stability of each concentration was evaluated through the phonon spectra calculations. All computations were carried out using the generalized gradient approximation of Perdew-Burke-Ernzerhof for the exchange-correlation potential of DFT. The calculations showed that all the Yb1-xCrxO (0.25 ≤ x ≥ 0.75) concentrations are thermodynamically feasible with significant formation energies (Yb0.25Cr0.75O = -502.429 Ry; Yb0.5Cr0.5O = -179.752 Ry and Yb0.75Cr0.25O = -565.792 Ry respectively). All of the concentrations are direct band gap half metals with dynamic stability for Yb0.5Cr0.5O and Yb0.75Cr0.25O but not for the Yb0.25Cr0.75O concentration.

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ES22-Qu

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Qu, Jianzhou - Department of Chemical Engineering and Columbia Electrochemical Energy Center; Columbia University, New York, NY

Title: Understanding Silica Coatings on the Platinum Surface via Calculated Pourbaix diagram from First Principles

Abstract: Current technology for water electrolysis requires highly purified water, which increases the overall energy requirements and thereby cost. Recently, it was found that a thin semi-permeable silica (SiO2) coating on the surface of Pt electrocatalysts can prevent the contamination from cations and can increase the stability of the electrocatalyst in complex solutions with negligible impact on the catalytic performance.1 Such coatings are not passive bystanders but can also affect the catalytic properties. However, to utilize the interplay of coating and catalyst, a better understanding of the coating/catalyst interface on the atomic scale is needed. We developed a first-principles approach for the calculation of interface Pourbaix diagrams to investigate the interactions between silica overlayers and the surface of platinum metal electrocatalysts.2 This tool allowed us to compare the pH- and potential-dependent stability of different SiO2 membrane terminations in contact with the Pt(111) surface in aqueous electrolytes. We also extended our approach to account for intermediates of the hydrogen evolution reaction (HER) to understand the HER reaction mechanism at the buried interface. We discuss how the dynamic nature of the interface may affect the catalytic properties of the SiO2/Pt system. We show that the interaction of silica membranes with Pt surfaces is environment-dependent and changes with the pH value of the electrolyte and the electrode potential. The SiO2/Pt system can be considered a simple model system for oxide-coated electrodes, and our approach can be readily extended to oxide coatings in other electrochemical devices such as batteries and other membrane-coated electrocatalysts.

References
1. Labrador, N. Y.; Songcuan, E. L.; De Silva, C.; Chen, H.; Kurdziel, S. J.; Ramachandran, R. K.; Detavernier, C.; Esposito, D. V. ACS Catal. 2018, 8 (3), 1767–1778. https://doi.org/10.1021/acscatal.7b02668.
2. Qu, J.; Urban, A. Potential and PH Dependence of the Buried Interface of Membrane-Coated Electrocatalysts. ACS Appl. Mater. Interfaces 2020, 12 (46), 52125–52135. https://doi.org/10.1021/acsami.0c14435.

Other authors: Urban, Alexander & Department of Chemical Engineering and Columbia Electrochemical Energy Center; Columbia University, New York, NY

Understanding Silica Coatings on the Platinum Surface via Calculated Pourbaix diagram from First Principles

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ES22-Saritas

ES22 Poster Session

Kayahan Saritas, Yale University

Title: Magnetic anisotropy densities through second order perturbation theory

Text: Piezoelectric ferromagnets (PFM) are characterized by having a piezo-active crystalline symmetry and possessing ferromagnetic ordering. Piezoelectrics change their dimensions when exposed to electric field which can lead to a change in the critical temperature of ferromagnetic interactions. Our first-principles calculations with data-mining approach reveal 2H-FeCl$_2$ as the only two-dimensional (2D) monolayered PFM with its critical temperature (Tc) near room temperature at 260K. Mermin-Wagner theorem asserts easy-axis magnetic anisotropy for ferromagnetic order in 2D materials. We explain the origin of easy-axis magnetic anisotropy in FeCl$_2$ quantitatively, by developing magnetic anisotropy {\it densities}. Our methods explain the origin of easy-plane and easy-axis anisotropies in VSe$_2$ and CrI$_3$ respectively. We show that the magnetic anisotropy of FeCl$_2$ can be enhanced up to 6-folds with only fractional hole doping. Our results offer design principles to aid the search for new 2D PFM for novel applications.

ES22-Shepherd,

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: James J. Shepherd, University of Iowa

TItle: A piecewise propagator for stochastic simulations of electrons with finite temperature

Abstract: Density matrix quantum Monte Carlo is a method to sample the N-body interacting density matrix for finite-temperature electronic structure. Switching the propagator to the interaction picture has been found to allow for the more effective sampling of a specific target inverse temperature, similar to how starting from a mean-field wavefunction speeds up the convergence in ground-state quantum Monte Carlo calculations. However, this has the drawback that every calculation only targets one temperature. To overcome this, we developed a piecewise propagator that switches the equations of motion at a target temperature [1]. The first phase of the calculation is performed at the same temperature and allows the energy to vary between the mean-field energy and the fully-interacting energy. The second phase of the calculation then allows temperature to change with the fully-interacting energy being calculated at every temperature point. The result is a significant improvement in the speed of our calculations. Example applications are shown for a variety of molecular Hamiltonians. [1] Van Benschoten, W. Z., Shepherd, J. J. (2022). Piecewise interaction picture density matrix quantum Monte Carlo. The Journal of Chemical Physics, 156, 184107; https://doi.org/10.1063/5.0094290

Other authors: William Z. Van Benschoten, University of Iowa

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ES22-Svendsen

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Mark Kamper Svendsen, Technical University of Denmark

Title: Momentum-Dependent Oscillator Strength Crossover of Excitons and Plasmons in Two-Dimensional PtSe2

Abstract: The 1T-phase layered PtX2 chalcogenides has attracted widespread interest due to its thickness dependent metal-semiconductor transition driven by strong interlayer coupling. However, its fundamental excitation spectrum remains poorly understood. Here we combine first principles calculations with momentum (q) resolved electron energy loss spectroscopy (q-EELS) to study the col- lective excitations in 1T-PtSe2 from the mono-layer limit to the bulk. Interestingly, the absence of long-range screening in the two-dimensional (2D) limit, inhibits the formation of long wave-length plasmons. Our work unravels the excited state spectrum of layered 1T-PtSe2 and establishes the qualitatively different momentum dependence of excitons and plasmons in 2D materials

Other authors: Jinhua Hong, Nanomaterials Research Institute, AIST, Tsukuba 305-8565, Japan

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ES22-Tang

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Tang, Fujie - Temple University

Title: Many-body effects in the X-ray absorption spectra of liquid water

Abstract: X-ray absorption spectroscopy (XAS) is a powerful experimental technique to probe the local order in materials with core electron excitations. Experimental interpretation requires supporting theoretical calculations. For water, these calculations are very demanding and, to date, could only be done with major approximations that limited the accuracy of the calculated spectra. This prompted an intense debate on whether a substantial revision of the standard picture of tetrahedrally bonded water was necessary to improve the agreement of theory and experiment. Here, we report a first-principles calculation of the XAS of water that avoids the approximations of prior work, thanks to recent advances in electron excitation theory. The calculated XAS spectra, and their variation with changes of temperature and/or with isotope substitution, are in good quantitative agreement with experiments. The approach requires accurate quasiparticle wave functions beyond density functional theory approximations, accounts for the dynamics of quasiparticles, and includes dynamic screening as well as renormalization effects due to the continuum of valence-level excitations. The three features observed in the experimental spectra are unambiguously attributed to excitonic effects. The preedge feature is associated with a bound intramolecular exciton, the main-edge feature is associated with an exciton localized within the coordination shell of the excited molecule, and the postedge feature is delocalized over more distant neighbors, as expected for a resonant state. The three features probe the local order at short, intermediate, and longer range relative to the excited molecule. The calculated spectra are fully consistent with a standard tetrahedral picture of water.

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ES22-Tokar

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Tokar, Kamil - Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia & Institute of Physics, Slovak Academy of Sciences, 845 11 Bratislava, Slovakia

Title: Charge ordering mechanism in silver difluoride from first principles

Abstract: Recently it was demonstrated that α-AgF2 (Pbca) structure represents an excellent silver analog of the parent compound of high-Tc superconducting cuprates. The structure consists of layers of spin-1/2 ions with a formally Ag(d9) electronic configuration, where unpaired electrons occupy the dx2−y2 orbitals antiferromagnetically coupled via a superexchange that involves F(p) orbitals. Possibly elimination of the AgF4 layers buckling could result in an enhanced AFM coupling that surpasses the oxocuprates [1]. In the current study, we reveal a competition between the Mott-Hubbard and intervalence charge transfer mechanism of electron localization in AgF2 using the Density Functional Theory (DFT) technique (standard DFT, DFT+U and hybrid DFT functionals) [2]. At reduced temperature and electron correlations α-AgF2 becomes metallic and dynamically unstable with respect to soft phonons that promote charge ordering. We show that charge density wave (CDW) instability is closely related to the Kohn anomaly and Fermi surface nesting. The long advocated KBrF4-type CDW Ag1+/3+F2 structure [3,4] and its facile transformation to the ground state α-Ag2+F2 phase was explained. Interplay between lattice, charge, and spin degrees of freedom in this seemingly simplistic binary metal fluoride was revealed.

Acknowledgment: K.T. and M.D. acknowledge the ERDF, Research and Innovation Operational Program for project (ITMS2014 +: 313011 W085), the Slovak Research and Development Agency (grant No. APVV-18-0168), and Scientific Grant Agency of the Slovak Republic (VG 1/0223/19). P.P. acknowledges the support by Narodowe Centrum Nauki (NCN, National Science Centre, Poland), Project No. 2017/25/B/ST3/02586. W.G. acknowledges Polish National Science Center (NCN) for Beethoven project (2016/23/G/ST5/04320). The computations were carried out using the Aurel supercomputing infrastructure in CC of Slovak Academy of Sciences acquired within the projects ITMS 26230120002 and ITMS 26210120002 supported by the ERDF, and infrastructure of Interdisciplinary Centre for Mathematical and Computational Modelling (ICM), University of Warsaw (Grants No. G62-24, No. GA83-34).

References:
[1] J. Gawraczynski, D. Kurzydłowski, R. A. Ewings, S. Bandaru, W. Gadomski, Z. Mazej, G. Ruani, I. Bergenti, T. Jaron, A. Ozarowski, S. Hill, P. J. Leszczyński, K. Tokár, M. Derzsi, P. Barone, K. Wohlfeld, J. Lorenzana, and W. Grochala, Proc. Natl. Acad. Sci. USA 116, 1495 (2019). [2] M. Derzsi, K. Tokár, P. Piekarz, and W. Grochala, Phys. Rev. B 105, L081113 (2022). [3] C. Shen, B. Žemva, G.M. Lucier, O. Graudejus, J.A. Allman, N. Bartlett, Inorg. Chem. 38, 4570 (1999). [4] K. Tokár, M. Derzsi, and W. Grochala, Comput. Mater. Sci. 188, 110250 (2021).

Other authors: Derzsi, Mariana Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia; & Piekarz, Przemyslaw Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31342 Kraków, Poland; & Grochala, Wojciech Center of New Technologies, University of Warsaw, 02089 Warsaw, Poland

Charge ordering mechanism in silver difluoride from first principles

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ES22-Wan

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Wan, Tianqi - Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY

Title: Spin State and Structural Stability of Ferropericlase up to 30 Mbar

Abstract: Ferropericlase (Fp), (Mg1-xFex)O, the second most abundant mineral in the Earth mantle, is expected to be an essential component of the deep mantle of terrestrial super-Earths. Thus, an understanding of Fp across a wide range of pressure, temperature, and iron concentrations is crucial to model the internal structure and dynamics of terrestrial exoplanets. Understanding pressure-induced electronic spin transitions in iron in Fp is a challenging problem given the strongly correlated nature of iron. Here, we present an LDA+Usc study of the structure and magnetic ground state of Fp from 200 GPa to 3 TPa in a range of iron concentrations, xFe, varying from ~3% to 25%. The quasiharmonic approximation (QHA) is used to compute the free energy and stability field of the B1 an B2 phases, as well as thermodynamic properties of these phases up to 3 Mbar. Such properties will be useful in modeling the mantle of super-Earth-type planets.

Other authors: Sun, Yang - Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA Renata, Wentzcovitch - Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA

Spin State and Structural Stability of Ferropericlase up to 30 Mbar

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ES22-Wang

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Wang, Hongjin - Columbia University

Title: pgm: A Python package for free energy calculation

Abstract: The quasi-harmonic approximation (QHA) is a powerful method for computing free energy and thermodynamic properties of materials at high pressures (P) and temperatures (T). However, anharmonicity, electronic excitations in metals, or both, introduce an intrinsic T-dependence on the phonon frequencies, which makes the QHA inadequate. Here we present a Python package, pgm, for free energy and thermodynamic property calculations. It is based on the concept of phonon quasiparticles and the phonon gas model (PGM). The free energy is obtained by integrating the entropy, which can be readily calculated for a system of phonon quasiparticles. This method is useful for getting free energy in anharmonic insulators and harmonic or anharmonic metals. The current implementation offers properties in a continuum range of states, bypassing the intensive VDoS calculations required by the traditional QHA method at each optimized structure. The necessary inputs are the volume-dependent ab-initio static energies and phonon frequencies for several discrete temperatures and the user-specified P- and T- range of the calculation. To accelerate the numerical computation, we employ techniques like just-in-time (JIT) compiling and parallel computing. We demonstrate successful applications of pgm to hcp-iron (Œµ-Fe) at extreme conditions [1] and cubic CaSiO3-perovskite [2], a strongly anharmonic system.

Other authors: Zhuang, Jingyi - Columbia University; Zhang, Zhen - Columbia University; Zhang, Qi - Columbia University; Wentzcovitch, Renata - Columbia University

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ES22-Wen

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Wen, Wen, Department of Chemistry, Carnegie Mellon University, Pittsburgh

Title: Genarris 4.0: Random Structure Generator for Organic/inorganic Interfaces

Abstract: Here we present Genarris 4.0, a random structure generator for organic/inorganic interfaces for seeding downstream interface structure prediction algorithms or machine learning models. Genarris 4.0 is written in python and interface with FHI-aims for interface energy evaluation and geometry relaxation. A volume estimation based on the number of molecules in film (Z) provides a maximum area estimation of interfaces. Epitaxy matrix is leveraged to generate film lattices commensurate with substrate lattice within max area limit. By identifying all compatible layer groups, diverse film lattices are sampled and then cleaved to slab structures by Ogre. A geometric surface matching algorithm is utilized to find the optimal displacement for each generated interface. A workflow with clustering and down selection is implemented to form a final pool of diverse and low-energy structures. We present the application of Genarris 4.0 to three representative organic/inorganic systmes: TCNE/Au(111), PTCDA/Ag(111), and naphthalene/Cu(111). For all three cases, the generated interface structures show great agreement with experimental findings.

Other authors:
Saeed Moayedpour, Department of Chemistry, Carnegie Mellon University, Pittsburgh.
Rithwik Tom, Department of Physics, Carnegie Mellon University, Pittsburgh.
manuel Bier, Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh.
Derek Dardzinski, Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh.
Noa Marom, Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh.

Genarris 4.0: Random Structure Generator for Organic/inorganic Interfaces

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ES22-Xu

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Xu, Jiahang, Department of Chemistry, the University of North Carolina at Chapel Hill

Title: Nuclear-Electronic Orbital Approach to Quantization of Protons in Periodic Electronic Structure Calculations

Abstract: The nuclear-electronic orbital (NEO) method is a well-established approach for treating nuclei quantum mechanically in molecular systems beyond the usual Born-Oppenheimer approximation. In this work, we present a strategy to implement the NEO method for periodic electronic structure calculations, particularly focused on multicomponent density functional theory (DFT). The NEO-DFT method is implemented in an all-electron electronic structure code, FHI-aims, using a combination of analytical and numerical integration techniques as well as a resolution of the identity scheme to enhance computational efficiency. After validating this implementation, proof-of-concept applications are presented to illustrate the effects of quantized protons on the physical properties of extended systems such as two-dimensional materials and liquid-semiconductor interfaces. Specifically, periodic NEO-DFT calculations are performed for a trans-polyacetylene chain, a hydrogen boride sheet, and a titanium oxide-water interface. The zero-point energy effects of the protons, as well as electron-proton correlation, are shown to noticeably impact the density of states and band structures for these systems. These developments provide a foundation for the application of multicomponent DFT to a wide range of other extended condensed matter systems.

Other authors:
Zhou, Ruiyi, Department of Chemistry, the University of North Carolina at Chapel Hill
Tao, Zhen, Department of Chemistry, Yale University
Malbon, Christopher, Department of Chemistry, Yale University
Blum, Volker, Thomas Lord Department of Mechanical Engineering and Material Science, Duke University
Hammes-Schiffer, Sharon, Department of Chemistry, Yale University
Kanai, Yosuke, Department of Chemistry, the University of North Carolina at Chapel Hill

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ES22-Zhang-Qi

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Zhang, Qi, Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY

Title: A systematic DFT study of thermal properties of several minerals using ab initio workflows

Abstract: Materials computations, especially of the ab initio kind, are intrinsically complex. These difficulties have inspired us to develop a workflow framework, express, to automate long and extensive sequences of the ab initio calculations. Various materials properties can be computed in express, e.g., static equation of state, phonon density of states, thermal equation of state, and other thermodynamic properties. It helps users in the preparation of inputs, execution of simulations, and analysis of data. It also tracks the operations and steps that users performed and thus can restore interrupted or failed jobs.

Here, we present the ab initio results facilitated by express of some minerals: akimotoite, albite, bridgmanite, coesite, corundum, diopside, lime, and stishovite. They cover a wide range of crystal systems. For each material, we calculate thermodynamic properties using the quasi-harmonic approximation with three groups of exchange-correlation functionals: local-density approximation (LDA), Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA), and the PBE functional revised for solids (PBEsol). These results are compared to other calculations and experiments, verifying the performance of these functionals and the utility of express. Besides the above advantages, express is also performant and extensible and runs on numerous high-performance platforms. It is open source, and everyone is welcome to use it.

Other authors: Wentzcovitch Renata, Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY

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ES22-Zhang

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Zhang, Zhen - Columbia University

Title: Anharmonic thermodynamic properties and phase boundary across the post-perovskite transition in MgSiO3

Abstract: To address the effects of lattice anharmonicity across the perovskite to post-perovskite transition in MgSiO3, we conduct calculations using the phonon quasiparticle (PHQ) approach. The PHQ is based on ab initio molecular dynamics and, in principle, captures full anharmonicity. Free energies in the thermodynamic limit (N‚Üí‚àû) are computed using temperature-dependent quasiparticle dispersions within the phonon gas model. Systematic results on anharmonic thermodynamic properties and phase boundary are reported. Both the local density approximation (LDA) and the generalized gradient approximation (GGA) calculations are performed to provide confident constraints on these properties. Anharmonic effects are demonstrated by comparing results with those obtained using the quasiharmonic approximation (QHA). The inadequacy of the QHA is indicated by its overestimation of thermal expansivity and thermodynamic Gr√ºneisen parameter and its converged isochoric heat capacity in the high-temperature limit. The PHQ phase boundary has a Clapeyron slope (dP/dT) that increases with temperature. This result contrasts with the nearly zero curvature of the QHA phase boundary. Anharmonicity bends the phase boundary to lower temperatures at high pressures. Implications for the double-crossing of the phase boundary by the mantle geotherm are discussed.

Other authors: Wentzcovitch, Renata, Columbia University

Anharmonic thermodynamic properties and phase boundary across the post-perovskite transition in MgSiO3

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ES22-Zhuang-1

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Zhuang, Jingyi - Columbia University, Lamont-Doherty Earth Observatory, Palisades

Title: Spin crossover in ferropericlase: beyond ideal solid solution model

Abstract: The pressure- and temperature-induced high spin (HS) to low spin (LS) crossover of Fe2+ ions in ferropericlase (Fp), Mg(1-x)FexO, affects mantle properties such as density, elasticity, thermal properties, iron partitioning between Fp and other co-existing phases, etc. It further affects how we interpret lower mantle observations. Here, we present results of thermodynamic properties computed using a free energy model that goes beyond the ideal HS-LS solid solution framework. As in the past, ab initio calculations were performed using the DFT+ USC method with structure and electronic configuration dependent USC. Results show the influence of iron-iron interactions (elastic or exchange type) on the pressure range of the crossover. Comparison with available experimental data shows considerably improved agreement over that of the ideal solid solution model.

Other authors: Sun, Yang, Columbia University, Lamont-Doherty Earth Observatory, Palisades Wentzcovitch, Renata M., Columbia University, Department of Applied Physics and Applied Mathematics

Spin crossover in ferropericlase: beyond ideal solid solution model

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ES22-Zhuang-2

2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Zhuang, Jingyi - Columbia University, Lamont-Doherty Earth Observatory, Palisades

Title: The post-perovskite transition in Fe- and Al-bearing bridgmanite

Abstract: The major phase of the Earth's mantle, (Al,Fe)-bearing bridgmanite, transitions to the post-perovskite (PPv) phase at Earth's deep lower mantle conditions. Despite extensive experimental and ab initio investigations, there are still important aspects of this transformation that need clarification. Here, we address this transition in (Al3+, Fe3+)-, (Al3+)-, (Fe2+)- and (Fe3+)-bearing bridgmanite using ab initio calculations. We find that the seismic features produced by the PPv transition depend distinctly on the chemical composition. For instance, Fe3+-, Al3+-, or (Al3+, Fe3+)-alloying increase the transition pressure, while Fe2+-alloying has the opposite effect. Consequently, the absence of a D" seismic discontinuity or signature of a double-crossing of the PPv phase boundary point to a Fe2+-poor and Fe3+-rich bridgmanite composition with profound implications for the redox state of the deep lower mantle. These chemistry-specific seismic features together, along with thermochemical equilibrium calculations will be fundamental for resolving the chemical composition of the D" region by direct inspection of tomographic images.

Other authors: Valencia-Cardona, Juan J., Logic Technology Development, Intel Corporation, Hillsboro, OR Wentzcovitch, Renata M., Columbia University, Department of Applied Physics and Applied Mathematics

The post-perovskite transition in Fe- and Al-bearing bridgmanite

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