Torsional Coriolis coefficients in a ‘regular’ vibrational basis for molecules with one pair of internal rotors

A general method for calculating the values of torsional Coriolis coefficients of molecules with internal rotation, with respect to an internal axis system, is described. This is done in view of the important role of torsional Coriolis interactions in the mechanisms, affecting the torsional splitting patterns. We choose a set of symmetrized vibrational coordinates where the displacements of all nuclei follow rectilinear trajectories in an internal axis system. The vibrational wavefunctions associated with these coordinates represent vibrational states where the splittings of the torsional components follow regular patterns, and departures from these basis vibrational states generate anomalous patterns. General expressions for the calculation of torsional Coriolis coefficients are obtained by the methods of basic molecular mechanics, and applications to special classes of molecules are shown and commented in detail. q 2004 Elsevier B.V. All rights reserved.