Berlin 2018 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 30: Focus Session: Frontiers of Electronic-Structure Theory: Correlated Electron Materials VI (joint session O/MM/DS/TT/CPP)
DS 30.9: Vortrag
Donnerstag, 15. März 2018, 12:30–12:45, HL 001
Calculations of charge and spin susceptibilities and quasiparticle energy shifts within the CASTEP plane-wave DFT code — •Vincent Sacksteder1, Evgeny Plekhanov2, Phil Hasnip3, Matt Probert3, Stewart Clark4, Keith Refson1, and Cedric Weber2 — 1Royal Holloway University of London, UK — 2Kings College London, UK — 3University of York, UK — 4University of Durham, UK
CASTEP is a pseudopotential based plane wave code which scales to the largest supercomputers and offers a wide feature set. Within CASTEP we have implemented calculation of the charge and spin susceptibility tensor, which describes the response to a perturbing charge or spin. We present corrections to the Kohn-Sham energies obtained by using the susceptibility tensor to screen Hartree-Fock exchange. In the static limit this is the SEX part of the COHSEX approximation, and if instead the dynamic susceptibility is used one obtains the GW approximation.
Our memory and CPU consumption scales linearly with the plane wave basis size, allowing thorough exploration of convergence with basis size, not only of the susceptibility itself, but of the SEX and GW quasiparticle shifts. We emphasize that our calculations are heavily parallelized, in exactly the same way as a standard DFT ground state calculation.
This work will allow first principles calculations of magnon spectra, exchange couplings, ionization potentials, and KKR and DMI coefficients.