A Spectroscopically Determined Potential Energy Surface for H+3

✍ Scribed by B.M. Dinelli; S. Miller; J. Tennyson

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 473 KB
• Volume: 163
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1994.1008

✦ Synopsis

A potential energy surface for (\mathrm{H}{3}^{+})is determined by adjusting 11 parameters from the ab initio surface of Lie and Frye ( (J). Chem. Phys. 96, 6784-6790, 1992) to a data set (243 \mathrm{H}{3}^{+})energy levels covering vibrational levels up to (3 v_{2}) and rotational levels up to (J=9). The surface is determined by successive refinements using variational calculations to reproduce the experimental data. A method which used cheaper but unconverged calculations for all but the final iteration of the fit is outlined. The resulting potential reproduces the observed data with a standard deviation of (0.053 \mathrm{~cm}^{-1}). Revised estimates of (\mathrm{H}{3}^{+})band origins up to (5 \nu{2}) are presented. Predictions for the fundamental frequencies using this potential are good for (\mathrm{D}{3}^{+})but poor for the mixed isotopomers (\mathrm{H}{2} \mathrm{D}^{+})and (\mathrm{D}{2} \mathrm{H}^{+}). It is suggested that these errors, which are about (0.5 \mathrm{~cm}^{-1}), are due the breakdown of the Born-Oppenheimer approximation. Comparisons are made with known non-Born-Oppenheimer terms for (\mathbf{H}{2}^{+})and (\mathbf{H}_{2}). (1994 Academic Press. Inc.