1303.0764 (R. Nourafkan et al.)

Electric polarization in correlated insulators    [PDF]

R. Nourafkan, G. Kotliar

We derive a formula for the electric polarization of interacting insulators, expressed in terms of the full Green's and vertex functions of the system. We use the formula to investigate changes in the electric polarization of the half-filled ionic Hubbard model in the DMFT framework. Interaction renormalizes both ionicity, and covalency of the system and competition between these renormalized quantities determines the electric polarization of a correlated band insulator. Based on a quasi-particle approximation, we comment that the LDA+U based calculations, which \emph{does not account} for the quasi-particle weight renormalization, will overestimate the electronic part of the electric polarization. This is sizable when the quasi-particle weight is far from one for active bands in the polarization.

View original: http://arxiv.org/abs/1303.0764