SINGLET TRIPLET ENERGY GAPS IN FLUORINE-SUBSTITUTED METHYLENES AND SILYLENES

We report singlet and triplet state splittings (ΔEST) for fluorine-substituted methylenes and silylenes using dissociation-consistent configuration interaction (CI) (based on generalized valence bond wave functions). These relatively simple CI calculations emphasize correlation consistency between the singlet and triplet states. Values of ΔE ST for CH2, CF2, SiH2, and SiF 2 are in excellent agreement with available experimental results, and we expect the predictions for the other cases CHF (14.5) and SiHF (41.3) to be equally accurate. This result strongly suggests that the correct choice among the experimental values for ΔEST of CHF is 14.7±0.2 kcal/mol. © 1990 American Institute of Physics.