Force field and assignment of the vibrational spectra of phenanthrene - anab initio study

A complete set of force constants and their corresponding scale factors in non-redundant local coordinates were obtained by fitting the ab initio Hart ree-Fock vibrational frequencies of phenanthrene-d(0) and -d(10) computed u sing 4-21G basis set to the experimental ones. The fitting reproduced the i n-plane fundamentals with an average deviation of 3.7 cm(-1) and the out-of -plane frequencies with an average deviation of 6.3 cm-(1) including C-H/C- D stretches, Using these force constants the potential energy distributions (PEDs) of the normal modes were obtained and based on the PEDs the earlier assignments were either confirmed or reassigned for all the fundamentals. The fitted force field was compared with the force fields of structurally r elated molecules. (C) 2000 Elsevier Science B.V. All rights reserved.