Local elastic constants in doped cesium halides

We have determined the local elastic constants around an impurity ion in a crystal of CsCl structure. A change in impurity mass and also the changes in the central and the noncentral interactions between the impurity and its nearest neighbors have been considered. Numerical estimates have been made for the local elastic constants of cesium halides containing ${\mathrm{Rb}}^{+}$, ${\mathrm{K}}^{+}$, ${\mathrm{Tl}}^{+}$, and ${\mathrm{In}}^{+}$ impurity ions. The results obtained for CsBr:${\mathrm{Tl}}^{+}$ and CsI:${\mathrm{Tl}}^{+}$ systems have been employed to evaluate the anharmonic coupling coefficients. The results are quite different from those of earlier workers.