Geometry, Force-Field, and Fundamental Frequencies of 4a,4b-Dihydrophenanthrene, a Scaled Quantum-Mechanical Force-Field Study.
by Zhou, X. F.; Liu, R. F.
Geometries of both cis- and trans-4a,4b-dihydrophenanthrene are optimized by restricted Hartree-Fock method with 4-21 G basis. At this level of theory, the trans-conformer is predicted 8.0 kcal/mol lower in energy than the cis one. The quadratic force field of the trans-conformer obtained from empirical scaling of the ab initio force constants reproduced the observed frequencies with mean deviation of about 10 cm-1. Based on the calculation an earlier assignment of two observed frequencies is confirmed and assignment of the rest of the observed frequencies is given. The observed frequencies at 1555 and 1534 cm-1 are concluded not to be fundamental frequencies of the subject molecule. This study shows again the practical value of the scaled quantum-mechanical force field method in the assignment of fundamental frequencies and identification of reaction products.
- Journal
- Chemical Physics Letters
- Volume
- 191
- Issue
- 5
- Year
- 1992
- Start Page
- 477-482
- URL
- https://dx.doi.org/10.1016/0009-2614(92)85412-4
- ISBN/ISSN
- 1873-4448; 0009-2614
- DOI
- 10.1016/0009-2614(92)85412-4