Internal mode vibrational interaction in plastic crystals: Application to the Raman spectra of strongly IR active modes.

The systematic development of the harmonic, intermolecular, internal mode interaction energy in terms of symmetry adapted Wigner functions of the molecular orientations is given for a plastic crystal. This development is used for the study of the Raman profile of a mode with a strong induced dipole-induced dipole interaction between the vibrating molecules. An approximate form of the profile is proposed, and compared with measurements made on NF3 by Gilbert and Nectoux. [ABSTRACT FROM AUTHOR]