Vibration-internal rotation-overall rotation interactions in CH3OH. II. Vibration introduced tau-dependence to the reduced kinetic energy coefficient for internal rotation

摘要

Vibration-internal rotation-rotation interaction theory has been used to calculate the tau-dependence of F, the reduced kinetic energy coefficient for internal rotation for CH3OH from molecular structure. The leading term is -3.2 x 10(-5) cos 3tau as a fraction of F-0. Smaller terms are 1.5 x 10(-7) cos 6tau and then -0.82 x 10(-7) cos 2tau and 5.0 x 10(-10) cos 4tau for the symmetry breaking terms of the vibrationally distorted molecule. These terms have not been included previously in torsion-rotation anaylses for CH3OH but should be compared with the fractional uncertainty in F-0 of +/-7 x 10(-7). A rough estimate of the T-independent vibrational contributions to F0 is of the order 4% with the largest contributors being the COH bend and OH stretch. (C) 2003 Elsevier Science (USA). All rights reserved. [References: 14]