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arXiv · 1405.1348

A mathematical perspective on density functional perturbation theory

Eric Cancès·Nahia Mourad
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Abstract

This article is concerned with the mathematical analysis of the perturbation method for extended Kohn-Sham models, in which fractional occupation numbers are allowed. All our results are established in the framework of the reduced Hartree-Fock (rHF) model, but our approach can be used to study other kinds of extended Kohn-Sham models, under some assumptions on the mathematical structure of the exchange- correlation functional. The classical results of Density Functional Perturbation Theory in the non-degenerate case (that is when the Fermi level is not a degenerate eigenvalue of the mean-field Hamiltonian) are formalized, and a proof of Wigner's (2n + 1) rule is provided. We then focus on the situation when the Fermi level is a degenerate eigenvalue of the rHF Hamiltonian, which had not been considered so far.

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Eric Cancès, Nahia Mourad. 2017-04-03. A mathematical perspective on density functional perturbation theory. https://doi.org/10.1088/09517715

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