Lattice embedding and equilibrium geometry of metal-halogen chains in the two-band extended Hubbard model

Abstract

Two-band extended Hubbard model studies show that the shift in optical gap of the metal-halogen (MX) chain upon embedding in a crystalline environment depends upon alternation in the site-diagonal electron-lattice interaction parameter (ε_M) and the strength of electron-electron interactions at the metal site (U_M). The equilibrium geometry studies on isolated chains show that the MX chains tend to distort for alternating ε_M and small U_M values.