Vibration-rotation levels of water beyond the Born-Oppenheimer approximation
Abstract
The value of the adiabatic correction to the Born-Oppenheimer electronic energy is calculated as a function of geometry for water using SCF wavefunctions. A mass-dependent adiabatic function is combined with high-accuracy ab initio electronic structure calculations due to Partridge and Schwenke. Vibrational band origins for H 2O, D 2O, T 2O, HDO, HTO and DTO are analysed. Unlike previous calculations on the H 3+ system, it is suggested that non-adiabatic effects are more important than adiabatic surface and effective masses of the heavy particles intermediate between the nuclear and atomic masses is found to significantly improve predictions of rotational term values. The adiabatic correction is found to be of particular importance for rotational levels with high Ka.
- Publication:
-
Chemical Physics Letters
- Pub Date:
- September 1996
- DOI:
- 10.1016/0009-2614(96)00872-X
- Bibcode:
- 1996CPL...260..381Z