Regensburg 2019 – scientific programme

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O: Fachverband Oberflächenphysik

O 4: Frontiers of Electronic-Structure Theory: Focus on the Interface Challenge I (joint session O/CPP/DS/TT)

O 4.6: Talk

Monday, April 1, 2019, 12:00–12:15, H9

Nonempricial hybrid functionals constructed through adjustable potential probes for band gap predictions of extended systems — •Thomas Bischoff, Igor Reshetnyak, and Alfredo Pasquarello — Chaire de Simulation a l'Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland

We describe a nonempirical procedure for achieving accurate band gaps of extended systems through the insertion of suitably defined potential probes. By enforcing Koopmans' condition on the resulting localized electronic states, we determine the optimal fraction of Fock exchange to be used in the adopted hybrid functional. As potential probes, we consider native defects, the extrinsic hydrogen impurity, and various adjustable potentials that allow us to vary the energy level of the localized state in the band gap and its degree of localization. By monitoring the delocalized screening charge, we achieve a measure of the hybridization with the band states, which can be used to improve the band gap estimate. Application of this methodology to AlP, C and MgO yields band gaps differing by less than 0.2 eV from experiment.