Computation of centrifugal distortion constants from the force field ; example of carbonyl sulphide

Abstract

Previous work [1] on the evaluation of rovibrational information directly from the force field has been modified to a form which solves for the energies, but not the eigenfunctions, for more than one value of J. The relative merits of the two approaches are discussed. The numerical values agree and the approaches are about of equal merit for vibrational origins and values of B_v for linear molecules, at least for OCS. However, extension to centrifugal distortion parameters is possible with the new form if the Coriolis terms are retained in the matrix of the hamiltonian. The calculations are carried out for OCS with the good agreement shown in table 3 using the previously determined force field.