J. Phys.: Condens. Matter 22, 095602 (2010)

SCI

Metal–insulator transitions in the half-filled ionic Hubbard model

A T Hoang

We study electronic phase transitions in the half-filled ionic Hubbard model with an on-site Coulomb repulsion U and an ionic energy _ by using the coherent potential approximation. For a fixed and finite _ two transitions from the band insulator via a metallic state to a Mott insulator are found with increasing U. The values of the critical correlation-driven metal–insulator transitions Uc1(_) and Uc2(_) are estimated. Our results are in reasonable agreement with the ones obtained by single-site dynamical mean-field theory and determinant quantum Monte Carlo simulation.