CALCULATION OF THE VIBRATIONAL ENERGY LEVELS OF TRIATOMIC MOLECULES

$^{1}$ V. Szalay, J. Mol. Spectrosc. in press. $^{2}$ J.N. Murrell, S. Carter, and L.O. Halonen, J. Mol. Spectrosc. 93, 307(1982). $^{3}$ A. R. Hoy, I. M. Mills, and G. Strey, Mol. Phys, 24, 1265(1972). $^{4}$ P. Jensen, Comp. Phys. Rep., 1, 1(1983), P. Jensen and P. R. Bunker, J. Mol. Spectrosc. 118, 18(1986). $^{5}$ J. C. Light, I. P. Hamilton, and J. V. Lill, J. Chem. Phys. 82, 1400(1985).Author Institution: Herzberg Institute of Astrophysics, National Research Council of CanadaThe vibrational energy levels of a number of triatomic molecules, $HCN, HNC, C_{3}, CH_{2}$, and $H_{2}O$ have been calculated from their ground electronic state potential energy surfaces. The calculations were carried out with a new method developed for molecules with large-amplitude internal motions in Ref.(1). This new method allowed us to use a wide variety of potential surfaces, from the most complicated Sorbie-Murrell type surface of the HCN--HNC isomerization $reaction^{2}$ to the simple Hoy-Mills-Strey potential of $H_{2}O^{3}$, with minor changes in the computer program. The results are discussed and compared to those of the variational and $nonrigid-bender^{4}$ calculations. The Schrodinger equation of the effective bending Hamiltonian of triatomic molecules has been solved by combining the power and advantages of the variational method and of the discrete variable $representation^{5}$