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Heisenberg exchange in La 2 CuO 4
Author(s) -
Van Oosten A. B.,
Broer R.,
Nieuwpoort W. C.
Publication year - 1995
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560560826
Subject(s) - antiferromagnetism , ground state , singlet state , exchange interaction , chemistry , excited state , cluster (spacecraft) , configuration interaction , heisenberg model , coupled cluster , condensed matter physics , atomic physics , physics , molecule , ferromagnetism , programming language , computer science , organic chemistry
We study the exchange interaction in the quasi‐2D antiferromagnetic high T c superconductor parent compound La 2 CuO 4 by all‐electron, embedded cluster methods. Our material model is the cluster Cu 2 O 11 , embedded in a matrix of point charges. The SCF ground state configuration is characterized by Cu 2+ and O 2− with the d‐hole oriented in the [CuO 2 ] 2− plane along the CuO bonds. We admix to this an excited SCF configuration that has one Cu‐hole transferred to the central O into the ground state configuration by nonorthogonal CI , while paying special attention to the variational balance of the singlet and triplet states. This results in a value for the exchange parameter of J = −120 meV, in good agreement with the experimental value of J = −128 meV. © 1995 John Wiley & Sons, Inc.