Thursday, February 28, 2013

1302.6756 (David Waroquiers et al.)

Band widths and gaps from the Tran-Blaha functional : Comparison with
many-body perturbation theory

David Waroquiers, Aurélien Lherbier, Anna Miglio, Martin Stankovski, Samuel Poncé, Micael J. T. Oliveira, Matteo Giantomassi, Gian-Marco Rignanese, Xavier Gonze
For a set of ten crystalline materials (oxides and semiconductors), we compute the electronic band structures using the Tran-Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TB09) functional. The band widths and gaps are compared with those from the local-density approximation (LDA) functional, many-body perturbation theory (MBPT), and experiments. At the density-functional theory (DFT) level, TB09 leads to band gaps in much better agreement with experiments than LDA. However, we observe that it globally underestimates, often strongly, the valence (and conduction) band widths (more than LDA). MBPT corrections are calculated starting from both LDA and TB09 eigenenergies and wavefunctions. They lead to a much better agreement with experimental data for band widths. The band gaps obtained starting from TB09 are close to those from quasi-particle self-consistent GW calculations, at a much reduced cost. Finally, we explore the possibility to tune one of the semi-empirical parameters of the TB09 functional in order to obtain simultaneously better band gaps and widths. We find that these requirements are conflicting.
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