Ab Initio Calculations of Radiative Transition Probabilities in Diatomic Molecules

Multiconfiguration self consistent field (MCSCF) and multiconfiguration reference configuration interaction (MCSCF-CI) techniques have been employed to calculate electric dipole moment and electronic transition moment functions of diatomic molecules and molecular ions. From these data radiative transition probabilities and lifetimes have been evaluated. It is demonstrated that the results are strongly dependent on electron correlation effects. Using highly correlated MCSCF-CI wavefunctions the radiative lifetimes are obtained with an accuracy of 10—15 percent, which is comparable to the uncertainties of the best experimental values. Often the calculated predictions appear to be more reliable than measured values. In some cases it has been found that empirical transition moment functions, which have been derived from measured relative intensities, exhibit an incorrect variation with the inter-nuclear distance.