A classical insight of the γ-Coriolis coupling in ethane-like molecules

Abstract

The mechanisms of interaction between the deformations of the two moieties of ethane-like molecules in degenerate vibrational modes are investigated by simple methods of classical mechanics. Special attention is given to γ-Coriolis interaction in degenerate vibrational states, which generates first order vibration-torsion coupling. It is shown that the level splitting due to tunneling through the torsional barrier in degenerate vibrational states is strongly affected by the value of the Coriolis ξ coefficient. Simple classical considerations can explain the recent experimental result that all degenerate normal modes of ethane form E1d, E2d paired representations of the G36(EM) molecular symmetry group.