Group-Theoretical Analysis of Lattice Vibrations in Molecular Crystals

Abstract

A practical method of analysing the external vibrations of molecular crystals according to the representation theory of space group is presented. The procedure, which is a direct extension of the method given for the ordinary crystal by one of the authors, is applicable to any complicated molecular crystal. The result should be useful to both neutron and Raman spectroscopy. Detail on hexamine, adamantane, and ammonium chloride crystals has been worked out, and the result for hexamine is compared with actual calculation by Cochran and Pawley.