MODEL POTENTIAL BASED ON TIGHT-BINDING TOTAL-ENERGY CALCULATIONS FOR TRANSITION-METAL SYSTEMS

A semiempirical model potential to simulate properties of fee transiti on metals is proposed. The attractive part of the potential has been o btained from a tight-binding Hamiltonian that takes into account the s ymmetry of the d orbitals and leads to a 2/3 power dependence on the e ffective coordination (or second moment of the local density of states ) instead of the usual square-root dependence. The repulsive interacti on is assumed to be of the Born-Mayer type. In order to use this poten tial for specific materials, four parameters are adjusted with experim ental data. We present two different parametrizations and calculate bu lk, defect, surface, and cluster properties comparing with experiment, ab initio calculations, and the usual second-moment approximation.