Claude Leforestier

Laboratoire de Structure et Dynamique  des Systemes Moleculaires et  Solides, CC014 Universite des Sciences et Techniques du Languedoc, Montpellier, FRANCE

We present a new method adapted to the calculation of  excited rovibrational states of semi-rigid molecules. It first relies on a description of the molecule in terms of polyspherical coordinates, in order to obtain a compact expression for the kinetic energy operator. This general description is then adapted to the molecule considered by defining curvilinear normal modes from a zero order harmonic Hamiltonian H₀, the solutions of which being used as the working basis set. As a result, only the difference H-H₀ has to be worked out numerically, H₀ being handled fully analytically. An application to the excited rovibrational states of the HFCO molecule is presented.