More realistic band gaps from meta-generalized gradient approximations: Only in a generalized Kohn-Sham scheme
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Journal ArticleDate
2016-05-24Author
Yang, ZHPeng, H
Sun, J
Perdew, JP
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http://hdl.handle.net/20.500.12613/5718
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10.1103/PhysRevB.93.205205Abstract
© 2016 American Physical Society. Unlike the local density approximation (LDA) and the generalized gradient approximation (GGA), calculations with meta-generalized gradient approximations (meta-GGA) are usually done according to the generalized Kohn-Sham (gKS) formalism. The exchange-correlation potential of the gKS equation is nonmultiplicative, which prevents systematic comparison of meta-GGA band structures to those of the LDA and the GGA. We implement the optimized effective potential (OEP) of the meta-GGA for periodic systems, which allows us to carry out meta-GGA calculations in the same KS manner as for the LDA and the GGA. We apply the OEP to several meta-GGAs, including the new SCAN functional [Phys. Rev. Lett. 115, 036402 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.036402]. We find that the KS gaps and KS band structures of meta-GGAs are close to those of GGAs. They are smaller than the more realistic gKS gaps of meta-GGAs, but probably close to the less-realistic gaps in the band structure of the exact KS potential, as can be seen by comparing with the gaps of the EXX+RPA OEP potential. The well-known grid sensitivity of meta-GGAs is much more severe in OEP calculations.Citation to related work
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http://dx.doi.org/10.34944/dspace/5700