Simple expressions for elastic constants c11, c12, and c44 and internal displacements of semiconductors

Simple expressions are given for elastic stiffness constants c11, c12, and c44 and Kleinman’s internal displacement parameter ζ. They all are represented by the bulk modulus and covalency alone, and predict fairly well the experimental results. These expressions are useful for getting a simple estimate of ζ as well as c11, c12, and c44.