Density-functional theory of polar insulators

R.W. Godby, X. Gonze, P. Ghosez

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We examine the density-functional theory of macroscopic insulators, obtained in the large-cluster limit or under periodic boundary conditions. For polar crystals, we find that the two procedures are not equivalent. In a large-cluster case, the exact exchange-correlation potential acquires a homogeneous ``electric field'' which is absent from the usual local approximations, and the Kohn-Sham electronic system becomes metallic. With periodic boundary conditions, such a field is forbidden, and the polarization deduced from Kohn-Sham wavefunctions is incorrect even if the exact functional is used.
Original languageEnglish
Pages (from-to)294-297
Number of pages3
JournalPhysical Review Letters
Issue number2
Publication statusPublished - 13 Jan 1997

Bibliographical note

© 1997 American Physical Society. Published in Physical Review Letters and uploaded in accordance with the publisher's self archiving policy.

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