A model of the narrow-band material with the electron–hole asymmetry

Metal-Insulator Transition in a Generalized Hubbard Model with Correlated Hopping at Half-Filling

“…In the present paper we consider a generalized Hubbard model including correlated hopping [1,2]. In such a model the hopping integrals, which describe hoppings of holes and doublons are different.…”

“…The important puzzle arising in an investigation of the generalized models is metal-insulator transition problem. In papers [2,16] a new mean-field approximation (MFA) which leads to the correct description of metal-insulator transition (MIT) has been proposed. In the present paper we use this MFA to study MIT in a generalized Hubbard model with correlated hopping at half-filling and zero temperature.…”

“…So, we start from the following generalization of the Hubbard model including correlated hopping [1,2]:…”

“…(σ denotes the spin projection which is opposite to σ), here we have used that J(iiji) = J(jiii) = J(iiij) in consequence of the matrix elements symmetry. Let us suppose (as in the papers [1,2]) that…”

“…Here we use MFA proposed in papers [2,16] to calculate the energy spectrum of electron system described by Hamiltonian (2.7).…”