Vibrational calculations on the biphenyl crystal. The mixing between low frequency internal and lattice modes.

Abstract

The low frequency optically active crystal vibrations of biphenyl have been calculated using atom–atom interaction potentials. The agreement with experimental data is good. It has been found that torsional and translational modes are very strongly coupled. The conformational change of the biphenyl molecule from gaseous to crystal state and the corresponding changes in the internal force field are discussed. Some assignments are reexamined taking into account the calculated results. The heat of sublimation is well reproduced from internal energy calculations.