A comparative ab initio study of torsion-inversion coupling in CH3NH2, CH3OH2+ and CH3CH2 center dot

作者：Bhatta Ram S; Gao Amy; Perry David S^*

来源：Journal of Molecular Structure (Theochem), 2010, 941(1-3): 22-29.

DOI：10.1016/j.theochem.2009.10.033

• Torsion
• Inversion
• Potential energy
• Torsion-inversion coupling

Two-dimensional, partially optimized torsion-inversion potential energy surfaces for methylamine, protonated methanol and ethyl radical were obtained by ab initio methods up to CCSD(T)/6-311++G(3df,2p). At this level, the zero-point corrected torsional barriers for CH3NH2 and CH3OH2+ were found to be 703.8 and 399.6 cm(-1). respectively, and corresponding inversion barriers are 1946.9 and 877.2 cm(-1). The torsional barrier for CH3CH2 center dot was found to be 21.2 cm(-1). Although the barrier heights are very different, the dominant torsion-inversion coupling term in each of the three cases has the same form, V-1.3 tau cos 3 alpha, where tau is the inversion angle and alpha is the torsional angle, and the magnitudes of the coupling, 280 <= V-1.3 <= 450 cm(-1), are similar.

• 出版日期2010-2-15