News Archive

Examples › Hyperbolic Exciton Polaritons

Confining light in a resonant cavity Read More›

Examples › Electronic structure of CrSBr: theory and experiment

Spin Disorder in CrSBr Read More›

Examples › Why TiSe₂ is a band insulator, not an excitonic insulator

Dynamical Symmetry Breaking in TiSe2 Read More›

Workshop › 5th Questaal School

Why first-principles descriptions of correlated systems are sometimes needed Read More›

Examples › Origins of Superconductivity in FeSe

A QSGW+DMFT description of superconductivity in Bulk, Intercalated, and Monolayer FeSe Read More›

Examples › Excitons in Cr{Cl,Br,I}₃

A QSGW description of the electronic structure and excitons in ferromagnetic CrX₃ compounds Read More›

Examples › An embedding scheme within the Quasiparticle Self-consistent GW approximation

An efficient, high-fidelity scheme to obtain the properties of a localized defect embedded in an otherwise periodic host Read More›

Workshop › 4th Daresbury Questaal School

Detailed electronic structure calculations for a proper description of the transport properties of magnetic Josephson junctions Read More›

Examples › Magnetism of Yttrium Iron Garnet

QSGW provides a parameter free description of magnetism in the YIG, the model material for spintronics and magnonics research Read More›

Examples › Origins of Superconductivity in LaFe₂As₂ and CaFe₂As₂

How incoherence from Hundness controls superconductivity in LaFe2As2 and CaFe2As2 Read More›

News › Questaal Methods Paper

A paper describing Questaal's functionality, including its basis set, its various implementations of density-functional theory and its two tracks of many-body theory. Read More›

Examples › Ab initio Description of Superconductivity in Sr₂RuO₄

How spin and charge parity combine to increase the superconducting critical temperature in Sr2RuO4 under strain Read More›

Examples › Density-functional Description of Spin Orbit Torque

Interfacial contribution to spin-orbit torque and magnetoresistance in ferromagnet/heavy-metal bilayers Read More›

Examples › Electrical transport of tetragonal CuMnAs

TB-LMTO-CPA was used to model electrical transport in tetragonal CuMnAs at finite temperature. Read More›

Examples › Hyperbolic Optical Dispersion in CuS

Anisotropic Plasmonic CuS Nanocrystals as a Natural Electronic Material with Hyperbolic Optical Dispersion Read More›

Examples › Energy band structure and optical properties of boron arsenide

State-of-the-art calculation of the electronic and optical properties of the newly emerging thermal transport semiconductor boron arsenide Read More›

Workshop › 3rd Daresbury Questaal school

We are pleased to announce the 3rd Daresbury Questaal school. It will take place 13-17 May 2019, at Daresbury Laboratory, UK. This is an opportunity for researchers to learn about advanced electronic structure and gain hands-on experience with Questaal's DFT/QSGW/BSE/DMFT functionality. The event is free to attend and local accommodation will be provided. Read More›

Examples › Spin-orbit Torques in CoPt Multilayers

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. Read More›

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 › Frolich contribution to energy band shifts in SrTiO₃

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. 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›