Date: October 3, 2007
Creator: DeYonker, Nathan J.; Ho, Dustin S.; Wilson, Angela K. & Cundari, Thomas R., 1964-
Description: This article discusses computational s-block thermochemistry with the correlation consistent composite approach. Abstract: The correlation consistent composite approach (ccCA) is a model chemistry that has been shown to accurately compute gas-phase enthalpies of formation for alkali and alkaline earth metal oxides and hydroxides (Ho, D.S.; DeYonker, N.J.; Wilson, A.K.; Cundari, T.R., J. Phys. Chem. A 2006, 110, 9767). The ccCA results contrast to more widely used model chemistries where calculated enthalpies of formation for such species can be in error by up to 90 kcal molˉ¹. In this study, the authors have applied ccCA to a more general set of 42 s-block molecules and compared the ccCA ∆Hf values to values obtained using the G3 and G3B model chemistries. Included in this training set are water complexes such as Na(H₂O)n⁺ where n = 1 - 4, dimers and trimers of ionic compounds such as (LiCl)₂ and (LiCl)₃, and the largest ccCA computation to date: Be-(acac)₂, BeC₁₀H₁₄O₄. Problems with the G3 model chemistries seem to be isolated to metal-oxygen bonded systems and Be-containing systems, as G3 and G3B still perform quite well with a 2.7 and 2.6 kcal mol⁻¹ mean absolute deviation (MAD), respectively, for gas-phase enthalpies of formation. The MAD ...
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