Systematic variation of Fock exchange in hybrid functionals: Effect on the structural, electronic and energetic properties of VO2

Abstract

The metal-semiconductor phase transition of vanadium dioxide VO2 is difficult to describe with conventional density-functional theory methods. In the present study we systematically varied the Fock exchange contribution in hybrid functionals in order to obtain a functional that can accurately describe the structural, electronic and energetic properties of both VO2-phases. For this purpose the hybrid functionals PBE0, HSE06 and LC-ωPBE, that are all derived from the GGA functional PBE, have been tested. Best results for the fundamental band gap and the relative phase stability of the re-parameterized functionals were obtained for 10% Fock exchange in PBE0, 20% Fock exchange in LC-ωPBE and 12.5% Fock exchange in HSE06. The re-parameterized functionals were furthermore tested in terms of their accuracy for calculated structural parameters. It was observed that PBE0-10 and HSE06-12.5 give the overall most accurate results.