Semiempirical determination of molecular motions associated with phonon modes in molecular crystals

An approach using piezomodulated Raman scattering is presented which permits determination of the molecular motions associated with the eigenmodes of molecular crystals. When coupled with a lattice dynamical calculation for the eigenmodes, the experiment can be used to validate the calculation. The case of 1,2,4,5-tetrabromobenzene is treated and it is shown that the phase relations of the piezomodulated Raman signals confirm the calculated eigenmodes. The Journal of Chemical Physics is copyrighted by The American Institute of Physics