CHARGE-ORDERED INSULATING STATE OF FE3O4 FROM FIRST-PRINCIPLES ELECTRONIC-STRUCTURE CALCULATIONS

The charge-ordered insulating state of Fe3O4 below the Verwey transiti on temperature has been studied by the modified local density approxim ation with Coulomb interaction correction method. The charge ordering is found to be a stable solution with an energy gap value of 0.34 eV ( the experimental value is 0.14 eV) in contrast to a uniform metallic s tate given by the standard local spin-density approximation. The calcu lated effective intersite Coulomb interaction is well screened (V = 0. 18 eV). It was shown that the change in electrostatic potential associ ated with the transition to a completely disordered state can close an energy gap leading to a metallic state.