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Abstract

Conventional band structure calculations in the local density
approximation (LDA) [1-3] are highly successful for many materials, but
miss important aspects of the physics and energetics of strongly
correlated electron systems, such as transition metal oxides and
f-electron systems displaying, e.g., Mott insulating and heavy
quasiparticle behavior. In this respect, the LDA + DMFT approach which
merges LDA with a modem many-body approach, the dynamical mean-field
theory (DMFT), has proved to be a breakthrough for the realistic
modeling of correlated materials. Depending on the strength of the
electronic correlation, a LDA + DMFT calculation yields the weakly
correlated LDA results, a strongly correlated metal, or a Mott
insulator. In this paper, the basic ideas and the set-up of the LDA +
DMFT(X) approach, where X is the method used to solve the DMFT
equations, are discussed. Results obtained with X = QMC (quantum Monte
Carlo) and X = NCA (non-crossing approximation) are presented and
compared, showing that the method X matters quantitatively. We also
discuss LDA + DMFT results for two prime examples of correlated
materials, i.e., V2O3 and Ce which undergo a Mott-Hubbard
metal-insulator and volume collapse transition, respectively. (c) 2006
WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.