Fractional charge perspective on the band gap in density-functional theory


Journal Article

The calculation of the band gap by density-functional theory (DFT) is examined by considering the behavior of the energy as a function of number of electrons. It is explained that the incorrect band-gap prediction with most approximate functionals originates mainly from errors in describing systems with fractional charges. Formulas for the energy derivatives with respect to number of electrons are derived, which clarify the role of optimized effective potentials in prediction of the band gap. Calculations with a recent functional that has much improved behavior for fractional charges give a good prediction of the energy gap and also εHOMO -I for finite systems. Our results indicate that it is possible, within DFT, to have a functional whose eigenvalues or derivatives accurately predict the band gap. © 2008 The American Physical Society.

Full Text

Duke Authors

Cited Authors

  • Cohen, AJ; Mori-Sánchez, P; Yang, W

Published Date

  • March 18, 2008

Published In

Volume / Issue

  • 77 / 11

Electronic International Standard Serial Number (EISSN)

  • 1550-235X

International Standard Serial Number (ISSN)

  • 1098-0121

Digital Object Identifier (DOI)

  • 10.1103/PhysRevB.77.115123

Citation Source

  • Scopus