October 30, 2018 | PAPERS · NONEQUILIBRIUM GREEN'S FUNCTIONS

We have demonstrated the feasibility of calculating the spin-orbit torques in layered systems within density-functional theory, augmented by an Anderson model to treat disorder. Terms beyond the usual damping-like and ﬁeld-like torques were found. While the torques that contribute to damping are almost entirely due to spin-orbit coupling on the Pt atoms, the field-like torque does not require it.

The Quasiparticle Self-Consistent GW approximation is combined with Dynamical Mean Field theory (DMFT). It is shown that by varying the positions of apical oxygen atoms, a metal-insulator transition can be induced in La2CuO4. This work also shows that optical conductivity can be well predicted by the theory and shows how spin and charge susceptibilities and the superconducting pairing order parameter, vary with the apical O displacement. QSGW+DMFT provides a new approach to handle strong correlations with predictive capability greatly superior to conventional methods such as DFT+DMFT.

A hands-on course highlighting Questaal's GW/DMFT/BSE capability. This is an opportunity for researchers to learn about advanced electronic structure and how to use the Questaal Suite.

The Lambrecht group at Case Western University estimated how phonons modify the band structure in SrTiO3. Isolating the Frolich part of the electron-phonon interaction (which is the dominant contribution for highly polar compounds), they estimated the reduction in the screened coulomb interaction W, and its effect on the QSGW band structure.

Recently, Brian Cunningham and Myrta Gruening incorporated ladder diagrams as an extension to the RPA polarizability. Ladder diagrams significantly improve agreement with experimental dielectric response functions. The QSGW framework makes it possible to address systems whose electronic structure is poorly described within the standard perturbative GW approaches with as a starting point density-functional theory calculations. The Figure shows the real and imaginary parts of the dielectric function for Ge.