Reduction of the Number of the Independent Orbit-Lattice Parameters

Abstract

It is shown that the long-wavelength approximation introduces some relations between the dynamic parameters which describe the orbit-lattice interaction. These relations, and also other relations which connect some of these parameters to the static parameters, are obtained from symmetry considerations. They reduce significantly the number of independent dynamic parameters, and this number is given for some common groups. The relations are derived explicitly for the $O_h$ group.