Comparison of independently calculated ab-initio normal-mode displacements for the three C-H stretching vibrations of methanol along the internal rotation path
Li-Hong Xu, Ronald M. Lees, Jon T. Hougen, Joel M. Bowman, Xinchuan Huang, Stuart Carter
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.
, Lees, R.
, Hougen, J.
, Bowman, J.
, Huang, X.
and Carter, S.
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 February 22, 2024)