Comparison of independently calculated ab-initio normal-mode displacements for the three C-H stretching vibrations of methanol along the internal rotation path

Published

March 19, 2014

Author(s)

Li-Hong Xu, Ronald M. Lees, Jon T. Hougen, Joel M. Bowman, Xinchuan Huang, Stuart Carter

Abstract

Comparison of graphical displays of normal-mode coefficients from recent quantum chemical projected-frequency calculations with analogous displays constructed after reexamination of results from more extensive higher-level calculations described earlier in the literature confirms the facts that: (i) no geometrical phase is accumulated in these coefficients when the methyl top undergoes one complete internal-rotation revolution with respect to the frame, and (ii) some of the coefficients, when plotted against the internal rotation angle, exhibit near-cusp-like behavior at one or two angles. The connection between these graphical displays and the magnitude of "Jahn-Teller-like" and "Renner-Teller-like" torsion-vibration interaction terms in a model Hamiltonian, as well as the connection between the lack of geometric-phase accumulation in these graphs and the number of conical intersections enclosed by one full internal-rotation motion, are briefly discussed.

Citation

Journal of Molecular Spectroscopy

Pub Type

Journals

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Keywords

ab initio, Cartesian displacements, internal rotation, methanol, normal modes, projected frequencies

Citation

Xu, L. , Lees, R. , Hougen, J. , Bowman, J. , Huang, X. and Carter, S. (2014), Comparison of independently calculated ab-initio normal-mode displacements for the three C-H stretching vibrations of methanol along the internal rotation path, Journal of Molecular Spectroscopy, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=915278 (Accessed October 20, 2025)