Accurate ab initio calculations for the 1B 1- 1A 1 separation in methylene

Abstract

Accurate ab initio calculations have been performed on the 1B 1 state of methylene. The basis set was of better than triple-zeta quality and included two sets of polarization functions. This work combined with previous work yields a 1A 1- 1B 1 separation of 1.07 eV. This determination is compared to those using Franck-Condon factors.