Theory of interionic forces in alkali halide crystals

The widely used Born-Mayer potential in the classical theory of ionic crystals is replaced by a quantum mechanical analytical potential form following the recent tight binding theory developed by Harrison. It is found that the crystalline data on interionic distance, separation energies, isothermal bulk modulus, and its pressure derivative for all the alkali halides can be fitted to a very good extent by taking the Madelung energy and Harrison's overlap potential form. It is emphasised that Harrison's overlap potential can be a useful tool for studying the properties of ionic crystals within the framework of conventional approach based on Madelung's energies. (author)