Rovibrational energy levels and transitions for H₃ ⁺ computed from a new highly accurate potential energy surface

Abstract

Bound rovibrational levels and selected transitions have been calculated for H3 + using a new potential energy surface (PES) computed by the CISD-R12-method. The present PES has an error of approximately 1 cm-1 in the relevant region around the minimum. This results in computed frequencies that reproduce experiment with a standard deviation of <0·31 cm-1 using nuclear masses for the motion of the three nuclei. In order to test non-Born-Oppenheimer effects different mass ratio definitions between nuclei and electrons have been analysed.