Shear modulus of cubic crystals

For cubic crystals the variability of the shear modulus is analyzed. Extreme values of the shear modulus and their directions are determined. It is shown that the dimensionless shear modulus depends on the crystal orientation and a positive dimensionless elastic parameter. The value of this parameter specifies, in particular, the ratio of maximum and minimum values of the shear modulus. The lists of the extreme values of shear moduli of various cubic crystals with negative Poisson's ratio, ordered by the magnitude of the elastic parameter, are given.