The significance of quadrupole-electric coefficients for the optical properties of nonmagnetic crystals

The physical significance of the quadrupole-electric tensor for the optical properties of nonmagnetic crystals is discussed. Some general symmetry properties between the optical material tensors are derived. As an example it is shown that the quadrupole-electric tensor induces the ellipticity of light which is reflected from crystals of the non centrosymmetric cubic classes 23 and ¯43m.