Volume 60, Number 4, November 2002
|Page(s)||601 - 607|
|Section||Condensed matter: electronic structure, electrical, magnetic, and optical properties|
|Published online||01 November 2002|
Density-functional study of the Mott gap in the Hubbard model
Departamento de Física e Informática,
Instituto de Física de São Carlos
Universidade de São Paulo - Caixa Postal 369, 13560-970
São Carlos, SP, Brazil
2 Departamento de Química e Física Molecular, Instituto de Química de São Carlos Universidade de São Paulo - Caixa Postal 780, São Carlos, 13560-970 SP, Brazil
Accepted: 29 August 2002
We study the Mott insulating phase of the one-dimensional Hubbard model using a local-density approximation (LDA) that is based on the Bethe Ansatz (BA). Unlike conventional functionals, the BA-LDA has an explicit derivative discontinuity. We demonstrate that, as a consequence of this discontinuity, the BA-LDA yields the correct Mott gap, independently of the strength of the correlations. A convenient analytical formula for the Mott gap in the thermodynamic limit is also derived. We find that in one-dimensional quantum systems the contribution of the discontinuity to the full gap is more important than that of the band-structure gap, and discuss some consequences this finding has for electronic-structure calculations.
PACS: 71.15.Mb – Density functional theory, local density approximation, gradient and other corrections / 71.10.Pm – Fermions in reduced dimensions (anyons, composite fermions, Luttinger liquid, etc.) / 71.10.Fd – Lattice fermion models (Hubbard model, etc.)
© EDP Sciences, 2002
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