Correlation-consistent singlet–triplet gaps in substituted carbenes

A b initio GVB-CI (generalized valence bond with configuration interaction) and MCSCF (multiconfiguration self-consistent-field) wave functions are used to calculate electronic state splittings for the lowest singlet and triplet states of substituted carbenes. The calculations emphasize correlation consistency between the two electronic states, resulting in short CI expansions. The singlet–triplet gaps (ΔEST) for CH2, CH(SiH3), CF2, CCl2, CHF, and CHCl are reported. They are in good agreement with available experimental data.