Electron Correlation in a Pair of Impurities in Semiconductors with Deformable Lattice

Abstract

The magnetic-nonmagnetic transition and the charge transfer instability in the two-electrons two-impurities system in semiconductors is studied by an exactly soluble one-dimensional model. The model is characterized by the on-site Coulomb repulsion and the linear electron-lattice coupling at the impurity sites and the electron transfer energy, in addition to the distance between the impurities and the local potential depth. The ground state adiabatic potential energy surfaces are calculated exactly and the phase boundaries for the magnetic-nonmagnetic transition as well as the charge symmetric-asymmetric transition are obtained. This model exhibits the features of Toyozawa’s two-electrons two-sites model in the case of the nearest neighbor pair and Anderson’s negative U system in the limit of infinitely distant pair.