Correlated hopping in the Falicov-Kimball model: a dynamical mean-field study

Abstract

We study the effects of correlated hopping in the two-dimensional (2D) Falicov-Kimball model by means ofan extension of the dynamical mean-field approximation (DMFA).The extension is based on the projection technique and the DMFA,in which nonlocal correlations are taken into account through static quantitiesof a relevant subspace.The effect of the correlated hopping is to introduce nonlocal self-energy componentswhich remain even at D→∞. We show thatthe sum rules of the spectral function and its moments are preserved.The spectral function obtained reveals significant nonlocal contributions which are absent in the DMFA.