Simple Approximate Physical Orbitals for GW Quasiparticle Calculations

Abstract

Generating unoccupied orbitals within DFT for use in GW calculations of quasiparticle energies becomes prohibitive for large systems. We show that, without any loss of accuracy, the unoccupied orbitals may be replaced by a set of simple approximate physical orbitals (SAPOs) made from appropriately prepared planewaves and localized basis DFT orbitals that represent the continuum and resonant states of the system, respectively. This approach allows for accurate quasiparticle calculations using only a very small number of unoccupied DFT orbitals, resulting in an order of magnitude gain in speed.

Publication
Physical Review Letters 107, 186404 (2011).
Date
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