Diffusion Monte Carlo using continuous real-space wave functions is one of the most accurate scalable many-body methods for solid state systems.
However, to date, spin-orbit interactions have not been incorporated into large-scale calculations at a first-principles level; only having been applied to small systems.
In this technique, we use explicitly correlated first-principles diffusion Monte Carlo calculations to derive an effective spin-orbit model Hamiltonian.
The simplified model Hamiltonian is then solved to obtain the energetics of the system.
To demonstrate this method, benchmark studies are performed in main-group atoms and monolayer tungsten disulfide, where high accuracy is obtained.
A major promise of this technique is that one can treat electron-electron interactions, spin-orbit effects, and one-body terms in effective Hamiltonians all on the same footing for bulk systems.
We envision this opening a new frontier for modeling spin-orbit effects in correlated materials.