Structural Phase Transition of Alkali Halides Using a Modified Interaction Model

A new interionic potential model is developed by taking into account (i) the effect of three body interactions, (ii) the recent values of van der Waals (vdW) potentials estimated from Kirkwood‐Muller formula, (iii) the repulsive hardness parameters evaluated from the overlap integrals using the exchange charge model, and (iv) the effect of coupling between overlap repulsive and van der Waals forces in terms of the Drude oscillator model. The modified potential model is capable of predicting correctly the relative stability of two structures viz. NaCl and CsCl structures. The calculated values of transition pressure are found to present close agreement with experimental data.