Accurate calculations of bond dissociation enthalpies with density functional methods

The homolytic dissociation enthalpies of various bonds (C-H, N-H, O-H, S-H, X-H, C-C, C-N, C-O, C-S, and C-halogen) have been computed by using five density functional methods (B3LYP, MPW1PW91, B3PW91, B3P86, and MPW1P86). The quality of these methods is comprehensively evaluated on the basis of the available experimental bond dissociation enthalpies, and it is found that the MPW1P86 has the best agreement, while B3LYP performs the largest deviations. Large deviations also are found at the sophisticated CCSD(T) level of theory. The restricted open-shell method underestimates the radical stability.