Ch. Hu, A comparative study of the singlet-triplet energy separation of carbenes using density functional theory and coupled-cluster methods, CHEM P LETT, 309(1-2), 1999, pp. 81-89
The singlet-triplet energy separation (Delta ES-T) of carbenes has been stu
died using density functional theory (DFT) and the single, double, plus per
turbative triple excitations coupled-cluster {CCSD(T)} approaches. Delta ES
-T predictions from DFT were compared with those of CCSD(T). We found that
BLYP and G96LYP predictions are closest to the CCSD(T) results, with the av
erage absolute deviations within 1 kcal/mol. Many of the tested functionals
overestimate Delta ES-T. It was observed that best comparisons are display
ed by the choice of correlation (LYP) functionals, while the effect of choo
sing among exchange functionals is less significant. The hybrid functionals
provide poorer, overestimated predictions for Delta ES-T. (C) 1999 Elsevie
r Science B.V. All rights reserved.