DEVELOPMENT OF AN EFFECTIVE INTERATOMIC POTENTIAL FOR TRANSITION-METALS AND ALLOYS - MODIFIED WILLS-HARRISON MODEL

This paper deals with the development of an effective interionic inter action for transition metals and alloys in the spirit of a hybridized pseudopotential tight-binding formalism, developed among others by Wil ls and Harrison. Stated briefly, the recipe consists in writing the to tal interionic interaction as a sum of contributions arising from near ly free s-electrons and that of tightly bound d-electrons. The s-d hyb ridization is also accounted for by allowing for the relative change i n the occupancy of s and d electron counts. This potential, although n ot taking into account the magnetic contribution, contains otherwise a ll the essentials of a physically meaningful interatomic interaction. In this paper, a modified version of the Wills-Harrison model is used to calculate the structural and cohesive properties of transition meta ls at 0 K. The calculated values are in reasonable agreement with the experimental ones. This method is also used to derive an effective int eratomic interaction for gamma-TiAl. The use of this potential in obta ining an estimate of point defect energetics in TiAl is discussed.