Benchmark calculations of reaction energies, barrier heights, and transition-state geometries for hydrogen abstraction from methanol by a hydrogen atom

Jingzhi Pu, Donald G. Truhlar

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

We report benchmark calculations of reaction energies, barrier heights, and transition-state geometries for the reaction of CH 3OH with H to produce CH 2OH and H 2. Highly accurate composite methods, such as CBS, G2, G3S, G3X, G3SX, and multi-coefficient correlation methods (MCCMs), are used to calibrate lower-cost methods. We also performed single-level CCSD(T) calculations extrapolated to the infinite-basis limit on the basis of aug-cc-pVXZ (X = 3, 4) correlation consistent basis sets. The benchmark high-level calculations give consensus values of the forward reaction barrier height and the reaction energy of 9.7 kcal/mol and - 6.4 kcal/mol, respectively. To evaluate the accuracy of cost-efficient methods that are potentially useful for dynamics studies of the title reaction, we further include the results obtained by hybrid density functional theory methods and hybrid meta density functional theory methods that have recently been designed for chemical kinetics. Results obtained by popular semiempirical methods are also given for comparison. On the basis of the benchmark gas-phase results, we suggest MC-QCISD/3, MC3BB, and BB1K as reasonably accurate and affordable electronic structure methods for calculating dynamics for the title reaction.

Original languageEnglish (US)
Pages (from-to)773-778
Number of pages6
JournalJournal of Physical Chemistry A
Volume109
Issue number5
DOIs
StatePublished - Feb 10 2005

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