Quantum tunneling rates of gas-phase reactions from on-the-fly instanton calculations

Beyer, Adrian N., Richardson, Jeremy O., Knowles, Peter J. ORCID: https://orcid.org/0000-0003-4657-6331, Rommel, Judith and Althorpe, Stuart C. 2016. Quantum tunneling rates of gas-phase reactions from on-the-fly instanton calculations. Journal of Physical Chemistry Letters 7 (21) , pp. 4374-4379. 10.1021/acs.jpclett.6b02115

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Abstract

The instanton method obtains approximate tunneling rates from the minimum-action path (known as the instanton) linking reactants to the products at a given temperature. An efficient way to find the instanton is to search for saddle-points on the ring-polymer potential surface, which is obtained by expressing the quantum Boltzmann operator as a discrete path-integral. Here we report a practical implementation of this ring-polymer form of instanton theory into the Molpro electronic-structure package, which allows the rates to be computed on-the-fly, without the need for a fitted analytic potential-energy surface. As a test case, we compute tunneling rates for the benchmark H + CH4 reaction, showing how the efficiency of the instanton method allows the user systematically to converge the tunneling rate with respect to the level of electronic-structure theory.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Advanced Research Computing @ Cardiff (ARCCA) Chemistry
Publisher:	American Chemical Society
ISSN:	1948-7185
Funders:	EPSRC
Date of First Compliant Deposit:	29 November 2016
Date of Acceptance:	19 October 2016
Last Modified:	04 May 2023 06:31
URI:	https://orca.cardiff.ac.uk/id/eprint/96488

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