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Examples › Metal-insulator transition in copper oxides induced by apex displacements
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. Read More›

Workshop › Many body response functions in the Questaal code
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. Read More›

news › Ladder Diagrams in QSGW
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. Read More›

Examples › Quasiparticle Self-Consistent GW
Metal-organic perovskite solar cells, CH3NH3PbI3 (MAPI) in particular, have attracted much attention recently because of their high power conversion efficiency and potential low cost. Read More›

Examples › QSGW + Spin-Dynamical Mean Field Theory Applied to Ni
Density-Functional theory, while being immensely popular thanks to its simplicity, nevertheless is limited in its reliability. The QuasiParticle Self-Consistent GW approximation, while more demanding than DFT, is vastly more reliable than DFT, or GW theory based on DFT, for calculation of optical properties in weakly correlated systems. Read More›

Examples › Principal Layer Green’s Functions
Many spintronic devices to emerge in recent years consist of spin transport through alternating, nanosized metallic layers Read More›

Examples › Green’s Functions LMTO
A new concept for very fast electronic devices has emerged in recent years. Called JMRAM, it relies on the rotation of the phase of a Cooper pair wave function when it passes through a thin magnetic layer. Read More›