Theoretical investigation of the Renner-Teller effect in Δ electronic states of tetra-atomic molecules. 2. Perturbative calculation of the vibronic spectrum in the 1¹Δ<inf>g</inf> state of B<inf>2</inf>H<inf>2</inf> from the linear molecule standpoint

Abstract

Second-order perturbative formulae for handling the Renner-Teller effect in Δ electronic states of symmetric tetra-atomic molecules with linear equilibrium geometry are derived. They are applied to calculate vibronic energy levels of the 11Δg state of B2H2. Perturbative parameters are derived by fitting the ab initio computed potential energy surfaces. The results of the calculations are compared with those obtained by means of a variational approach. © 1999 Taylor & Francis Group, LLC.