Harmonic dynamical behaviour of thallous halides

Abstract

Harmonic dynamical behaviour of thallous halides (TlCl and TlBr) have been studied using the new van der Waals three-body force shell model (VTSM), which incorporates the effects of the van der Waals interaction along with long-range Coulomb interactions, three-body interactions and short-range second neighbour interactions in the framework of rigid shell model (RSM). Phonon dispersion curves (PDC), variations of Debye temperature with absolute temperature and phonon density of state (PDS) curves have been reported for thallous halides using VTSM. Comparison of experimental values with those of VTSM and TSM are also reported in the paper and a good agreement between experimental and VTSM values has been found, from which it may be inferred that the incorporation of van der Waals interactions is essential for the complete harmonic dynamical behaviour of thallous halides.

Effect of van der Waals and three body interactions on the lattice dynamics of Ionic crystals: an application to SrO

“…Since no experimental values on these properties have been reported so far, we are unable to comment on them but our results will help the experimental workers to analyze their data in future. This study gets strong support from recent publications of our research group [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. To conclude we can say that the present model SOE VTSM has successfully explained the phonon properties which include phonon dispersion curves variations of  D with temperature T and combined density of states.…”

Theoretical analysis of phonon dynamical behaviour of Cesium Chloride at various temperatures

“…In fact, the present model VTSM has revealed much better descriptions of dynamical properties of these compounds than those obtained by rigid shell model [26], deformation shell model [19], breathing shell model [20], extended three-body force shell model [1]. This study gets strong support from recent publications of our research group [32][33][34][35][36][37][38][39][40][41][42][43]. The induction of van der Waals interactions is much essential in the study of lattice dynamics of alkali halides crystals.…”