Phys. Rev. B 74, 161103(R) (2006) [4 pages]Effect of spatial nonlocality on the density functional band gap
We show that for a large class of exchange-correlation functionals the local exchange-correlation potential obtained within an optimized effective potential severely underestimates the band gap. On the other hand, the corresponding nonlocal potential obtained from a generalized Kohn-Sham scheme provides a much better description of the band gap, in good agreement with experiments. These results strongly indicate that a local exchange-correlation potential, however good the exchange-correlation approximation, cannot capture the delicate interplay between correlation effects and spatial localization in the KS band structure, unless the (cumbersome) contribution from the derivative discontinuity of the exchange-correlation energy functional is considered. © 2006 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.74.161103
DOI:
10.1103/PhysRevB.74.161103
PACS:
71.15.Mb, 71.20.−b
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