Band origins for water up to 22 000 cm −1: A comparison of spectroscopically determined potential energy surfaces

Abstract

Rovibrational energy levels are calculated for water using four potential energy surfaces recently determined from spectroscopic data. By using Radau coordinates and a discrete variable representation of the angular coordinate the lowest 172 band origins are converged to 0.1 cm −1 or better. These results are compared to the 62 observed band origins for H 2 16O. Comparisons are also made for the J = 1 and J = 2 term values for the lowest 10 vibrational states. The best potential, due to Jensen ( J. Mol. Spectrosc. 133, 438 (1989)), reproduces the observed band origins with a standard deviation of 6.4 cm −1 and 0.10 cm −1 for the term values. This potential shows a small systematic error in that it overestimates many higher band origins. Estimates are given for all the unobserved band origins below 22 000 cm −1.