The low-lying electronic states of MgO.

The low-lying singlet and triplet states of MgO have been studied using a SA-CASCF/IC-MRCI approach using the aug-cc-pV5Z basis set. The spectroscopic constants (r e , w e , and T e ) are in good agreement with the available experimental data. The computed lifetime for the B state is in excellent agreement with two of the three experimental results. The d state lifetime is in good agreement with experiment, while the computed D state lifetime is about twice as long as experiment.