Spontaneous break of symmetry in molecular crystals

Abstract

The structural dissymmetry of crystals with coordinated groups of atoms performing some motion in the crystal is described in terms of the theory of hindered molecular motion based on the dynamic principles of invariance for the extended angular jump model. The spontaneous break of the symmetry in the ordered ammonium chloride phase is discussed with the invocation of the proton-relaxation data. © 2007 MAIK "Nauka/Interperiodica".