A force field derived by density functional theory for 4-ethylimidazole: use of the ultraviolet resonance Raman intensities to check the vibrational analysis

✍ Scribed by H. Gallouj; P. Lagant; G. Vergoten

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 238 KB
• Volume: 28
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(199711)28:11<909::aid-jrs187>3.0.co;2-x

✦ Synopsis

The vibrational wavenumbers of 4-ethylimidazole were obtained from ab initio studies based on the density functional theory approach. The assignments of the theoretical wavenumbers obtained after scaling of the internal force constants were performed by comparison with the observed Raman and infrared wavenumbers in histidine and 4-methylimidazole. The resonance Raman intensities were obtained from the changes in bond orders occurring during the lowest p Ç p* electronic transition. It can be seen that the change from Hartree-Fock to post-Hartree-Fock methods leads to revision, to some extent, of both electronic transitions and normal mode assignments.