Newab InitioPotential Energy Surfaces for the Renner-Teller Coupled11A′and11A′′States of CH2

[摘要] Newab initiopotential energy surfaces (PESs) for the two lowest-lying singlet11A′ and11A′′ electronic states of CH2, coupled by the Renner-Teller (RT) effect and meant for the spectroscopic study, are presented. The surfaces are constructed using a dual-level strategy. The internally contracted multireferenceconfiguration interaction calculations with the Davidson correction, using theaug-cc-pVQZbasis set, areemployed to obtain 3042 points at the lower level. The core and core-valence correlation effects are takeninto account in theab initiocalculations with a modified optimizedaug-cc-pCVQZbasis set for the higher-level points. The analytical representations of these PESs, with the inclusion of the nonadiabatic RT terms,are obtained by the nonlinear least-squares fit of the calculated points to three-body expansion. Quantumdynamical calculations are performed on these PESs, and the computed vibronic energy levels for the twosinglet electronic states are in excellent agreement with experiment.

[学科分类] 物理化学和理论化学