THE EFFECT OF BAND STRUCTURE AND ELECTRON-ELECTRON INTERACTIONS ON THE METAL-INSULATOR TRANSITIONS IN Ti2O3 AND V2O3

Abstract

A previous single-electron band calculation for Ti2O3 and V2O3 is modified including self consistently the effect of intra-atomic electron-electron interactions by means of a generalized Hubbard Hamiltonian. For Ti2O3 it is shown that the assumption of different occupations for the a1g and the ep bands results in a creation of a gap which is not associated with magnetic moments. This mechanism of gap creation is consistent with the experimental effects of temperature and doping V on the transition and the c/a ratio. For V2O3 if is shown that a gap is created in the antiferromagnetic phase where different occupations are assumed for the different spin states. This gap is of the Hubbard type but has the complexity of the problem which might be the explanation for the first order nature of the transition