Ab initio potential energy surfaces of large-amplitude motions for quasi-symmetric top molecules: CH3NCO

✍ Scribed by Jacek Koput

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 503 KB
• Volume: 242
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(95)00754-r

✦ Synopsis

The potential energy surface of methyl isocyanate, CH3NCO , has been investigated in quantum mechanical ab initio calculations at the SCF, MP2-MP4, and CCSD(T) levels of theory. The total energy of the molecule was calculated as a function of the coordinates of the two large-amplitude motions: the CNC bending motion and internal rotation of the methyl group. At the most advanced level employed, CCSD(T) with cc-pVTZ basis set, the barriers to linearity of the CNCO skeleton and to internal rotation of the methyl group were determined to be 920 and 22 cm -~, respectively. The theoretical results are in good agreement with experimental data and consistent with the quasi-symmetric top model of the molecule.