The low-frequency vibrations of the flexible molecule tetraphenylmethane in its crystalline state are calculated and compared with experiment. This case was selected for a test of an empirical potential function because of the availability of unambiguous assignments for a large number of low-frequency vibrations. Many of these vibrations are expected to be mixtures of internal and external motions. The dynamic lattice calculation performed with the QCFF-PI procedure employed no adjustment of the parameters of the semiempirical potential function determined in previous studies. Excellent agreement is observed between the calculated and observed structure and 14 vibrations below 160 cm-1.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry