Variation of electronic polarizabilities and sizes of ions in crystals under hydrostatic pressure

A model, based on the energy level analysis performed by Ruffa and empirical relation between polarizability and ionic radius, has been developed to study the variation of electronic polarizabilities and sizes of ions in crystals under hydrostatic pressure. The model has been applied to investigate the photoelastic behavior of alkali halides and MgO. The strain derivatives of electronic polarizabilities and dielectric constants thus evaluated present a good agreement with experimental data and other theoretical investigations.