CCSD(T) determination of the vibrational structure in the Ã2Σ+ ← X̃2Π spectrum of CCO-
Résumé
An ab-inito quartic force field of CCO- in its first excited state Ã2Σ+ is calculated from an aug-cc-VTZ basis set at CCSD(T) level of theory in order to compute the vibrational energy levels in the range 600-4800 cm-1. A variational-perturbational approach is used to diagonalize the most important vibrational configurations constructed from harmonic vibrational wave functions. The result agree well with the most reliable experimental values studied in a neon matrix and predict as yet unobserved overtones bands in the vibrational structure of the Ã2Σ+ → X̃2Π spectrum of CCO-. © 2001 American Chemical Society.