Cj. Calzado et Jp. Malrieu, Comparison between explicitly correlated and density functional theory calculations in mixed-valence model systems, CHEM P LETT, 317(3-5), 2000, pp. 404-413
Considering simple model problems, symmetric mixed-valence compounds an stu
died by both accurate ab initio configuration interaction (CI) and standard
(B3LYP) density functional theory (DFT) calculations. The DFT estimates of
the effective hopping integral t for mixed-valence compounds are generally
smaller (by 20%) than the CI values, in contrast to those of the exchange
coupling constant in magnetic systems which are usually overestimated. Qual
itatively divergent behaviors of DFT versus CI results have been found in s
ome cases. Possible origins of these discrepancies are discussed. (C) 3000
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