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Kinetic isotope effect in malonaldehyde determined from path integral Monte Carlo simulations

Huang, Jing and Buchowiecki, Marcin and Nagy, Tibor and Vaníček, Jiří and Meuwly, Markus. (2014) Kinetic isotope effect in malonaldehyde determined from path integral Monte Carlo simulations. Physical Chemistry, Chemical Physics, 16 (1). pp. 204-211.

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Official URL: http://edoc.unibas.ch/dok/A6223427

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Abstract

The primary H/D kinetic isotope effect on the intramolecular proton transfer in malonaldehyde is determined from quantum instanton path integral Monte Carlo simulations on a fully dimensional and validated potential energy surface for temperatures between 250 and 1500 K. Our calculations, based on thermodynamic integration with respect to the mass of the transferring particle, are significantly accelerated by the direct evaluation of the kinetic isotope effect instead of computing it as a ratio of two rate constants. At room temperature, the KIE from the present simulations is 5.2 ± 0.4. The KIE is found to vary considerably as a function of temperature and the low-T behaviour is dominated by the fact that the free energy derivative in the reactant state increases more rapidly than in the transition state. Detailed analysis of the various contributions to the quantum rate constant together with estimates for rates from conventional transition state theory and from periodic orbit theory suggest that the KIE in malonaldehyde is dominated by zero point energy effects and that tunneling plays a minor role at room temperature.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Physikalische Chemie (Meuwly)
UniBasel Contributors:Meuwly, Markus
Item Type:Article, refereed
Publisher:Royal Society of Chemistry
ISSN:1463-9076
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:05 Dec 2016 12:28
Deposited On:27 Mar 2014 13:13

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