Calculations on real materials provide valuable insight into their microscopic and macroscopic properties; not only their unperturbed state but under change of outside parameters, such as temperature, pressure or strain. As real materials contain a large number of particles, an exact solution is computationally infeasible. To address this challenge, sophisticated approximate methods must be developed. One such approach, is the GW method, which arises from perturbative treatment of the interaction. As an ab initio technique, GW requires only basic information about the system and a reasonable initial guess to begin the calculation. We apply the self-consistent GW method to two systems of interest: α-Sn and BiVO3.Tin in its low-temperature phase, α-Sn, exhibits intriguing topological properties, which have been extensively studied via angular resolved photoemission spectroscopy (ARPES) experiments and density functional theory (DFT). Using an exact two-component formalism for the Dirac Hamiltonian to capture the spin-orbit-coupling, our finite-temperature ab initio GW calculations of α-Sn under strain along the c-axis reveal features indicative of topological nature. Further, we find a possible high temperature phase in α-Sn.In contrast, BiVO3 has received limited attention to date, as it was only recently synthesized under high-temperature and high-pressure conditions using a diamond anvil cell. No experimental band structure is currently available, and previous computational studies have been focused on density functional theory (DFT), predicting an antiferromagnetic metallic phase. Our self-consistent GW analysis of BiVO3 indicates a significantly reduced metallically compared to these earlier predictions. We further determine the orbitals contributing to the antiferromagnetic state and confirm the stability of the a-type antiferromagnetic state in self-consistent GW.
Selina Dirnböck (Thu,) studied this question.