A weak-mode representation of floppy molecules. Part IV. Spectroscopic states of model HCN and CNH Original Research Article

The vibrational eigenstates of HCN and CNH and the states above the isomerization barrier, delocalized to both isomers, are analyzed (according to the automatic procedure of Saint-Espès et al., Chem. Phys., 188 (1994) 33), for the potential energy surface of Murrell et al. (J. Mol. Spectrosc., 93 (1982) 307). The high-energy vibrational level distributions of both isomers turn out to be particularly complicated because of an over-pronounced shoulder of the potential energy surface on the CNH side. The results presented here being thus for a model, this work simply aims at testing the efficiency of the automatic assignment procedure in a particularly delicate case, not at providing numerical results for the high-lying vibrational levels to be compared with experimental results.