Unified Study of Lattice Dynamic of Potassium Iodide (KI)

A unified description of a series of Phonon properties of potassium iodide (KI) by means of van der Waals three-body force shell model [VTBFSM] is presented. This model includes van der Waals interactions (VWI) and three-body interactions (TBI) in the framework of both ion polarizable rigid shell model (RSM). The present model has revealed much better descriptions of IR/Raman spectra and anhormonic and other dynamical properties of KI. A comparative study of the dynamical behaviour of KI has also been carried out. Agreement between the theoretical and experimental results, indicate the necessity of the adopted unified approach for the complete description of ionic crystals having NaCl structure. We conjecture that the incorporation of van der Waals interactions is essential for the complete harmonic dynamical behavior of KI.