Comparison of quantum dynamics and quantum transition state theory estimates of the H + CH4 reaction rate

Stefan Andersson, Gunnar Nyman*, Andri Arnaldsson, Uwe Manthe, Hannes Jonsson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

120 Citations (Scopus)

Abstract

Thermal rate constants are calculated for the H CH4 f CH3 H2 reaction employing the potential energy surface of Espinosa-Garci a (Espinosa-Garci a, J. J. Chem. Phys. 2002, 116, 10664). Two theoretical approache are used. First, we employ the multicon?gurational time-dependent Hartree method combined with ?ux correlation functions. In this way rate constants in the range 225 400 K are obtained and compared with previous results using the same theoretical method but the potential energy surface of Wu et al. (Wu, T. Werner, H.-J.; Manthe, U. Science 2004, 306, 2227). It is found that the Espinosa-Garci a surface results in larger rate constants. Second, a harmonic quantum transition state theory (HQTST) implementation of instanto theory is used to obtain rate constants in a temperature interval from 20 K up to the crossover temperatur at 296 K. The HQTST estimates are larger than MCTDH ones by a factor of about three in the common temperature range. Comparison is also made with various tunneling correctins to transition state theory and quantum instanton theory.

Original languageEnglish
Pages (from-to)4468-4478
Number of pages11
JournalJournal of Physical Chemistry A
Volume113
Issue number16
DOIs
Publication statusPublished - 23 Apr 2009

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