Development of a new interatomic potential for the modeling of ligand field effects

A new type of interatomic potential, based on the angular overlap model, ha s been developed in order to model compounds containing "nonspherical" tran sition metal ions. The parametrized function has been implemented within th e computational package GULP. We present full details of the energy and ana lytical derivatives, as well as the symmetry adaptation of the algorithms. The model has been successfully applied to LaMnO3 and Mn2O3, with the Mn-O bond distances within the MnO6 octahedra and the lattice parameters being r eproduced to within 0.33% of those determined experimentally. Both the shor t-ranged repulsive potential and our new potential parameters were empirica lly fitted to reproduce the former structure and then successfully transfer red to model the latter without modification.