Vibronic coupling for H2CO and CO2 Original Research Article

We calculated the optical oscillator strength (OOS) for the sum of the vibronic excitations related to the valence electronic A1→A2 state in H2CO and the inner-shell C 1s (2σg→5σg) state of the CO2 molecule. Electronic transition moments are calculated along the normal coordinates using configuration interaction wave functions. A quantum mechanical sum rule is used, which provides a final expression for the OOS that depends only on the ground-state vibrational function. The present results are in excellent agreement with the experiment. In particular, the calculation for C 1s (2σg→5σg) vibronic coupling is reported for the first time.