Effect of three-body forces on Schottky defect energy of alkali halides

Abstract

A three-body interaction potential (TBP) has been developed for the study of point defect properties of alkali halides. This TBP consists of the short-range van der Waals (vdW) attraction and overlap repulsion effective upon the second neighbours. These three-body interactions owe their origin to charge transfer mechanism caused by the deformation of electron shells of overlapping ions. We have, for the first time, incorporated the effects of TBP in the framework of polarizable point ion (PPI) model and used this modified PPI model to calculate the Schottky defect formation energy of alkali halides. This model has been found to take proper account of their elastic and dielectric properties. Also, the Schottky defect formation energies, obtained by us, have shown reasonably better agreements with their experimental data than achieved by earlier workers.