Résumé
We present a general purpose program, based on exact quantum methods, which allows one to study the spectroscopical properties of polyatomic molecules and to follow the time evolution of single initial states. The program displays no restriction concerning the molecule or basis set size, and the Hamiltonian specifications are done in a flexible, symbolic way, similar to the usual normal (or local) mode expansion. Also it makes full use of the vector and parallel facilities available on the present supercomputers. Three different recent techniques have been implemented, namely the recursive residue generation method, the Chebyshev time-propagator, and an active space method. The possibilities of the program are illustrated in the case of the CD
3H molecule, including all vibrational degrees of freedom. We first present an infrared spectrum determination, with special emphasis on the overtones of the C-H stretch mode, up to the fifth one (circa 16000 cm
-1). We then show how the intramolecular vibrational relaxation from these highly excited local modes can be computed. The basis sets used in these studies range from 10
5 to several millions states.