Performance of the correlation consistent composite approach for transition states: a comparison to G3B theory.
The correlation consistent composite approach (ccCA) was applied to the prediction of reaction barrier heights (i.e., transition state energy relative to reactants and products) for a standard benchmark set of reactions comprised of both hydrogen transfer reactions and nonhydrogen transfer reactions (i.e., heavy-atom transfer, SN2, and unimolecular reactions). The ccCA method was compared against G3B for the same set of reactions. Error metrics indicate that ccCA achieves "chemical accuracy" with a mean unsigned error (MUE) of 0.89 kcal/mol with respect to the benchmark data for barrier heights; G3B has a mean unsigned error of 1.94 kcal/mol. Further, the greater accuracy of ccCA for predicted reaction barriers is compared to other benchmarked literature methods, including density functional (BB1K, MUE=1.16 kcal/mol) and wavefunction-based [QCISD(T), MUE=1.10 kcal/mol] methods.
Grimes
Thomas V
TV
Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM), University of North Texas, P.O. Box 305070, Denton, Texas 76203-5070, USA.
Wilson
Angela K
AK
DeYonker
Nathan J
NJ
Cundari
Thomas R
TR