The nth-order elastic constants of centrosymmetric ionic solids

Abstract

Expressions for the nth-order elastic constants of ionic centrosymmetric solids have been developed using a central crystal-potential expansion. The comparison of the Coulomb contribution to the third-order elastic constants of alkali halides with calculations of Nran'yan and Ghate show disagreements as large as 139%. It is shown that the disagreements may be due to the poor convergence of the Coulomb sums in the previous calculations.