Kinetic isotope effects and how to describe them

Karandashev, Konstantin and Xu, Zhen-Hao and Meuwly, Markus and Vaníček, Jiří and Richardson, Jeremy O.. (2017) Kinetic isotope effects and how to describe them. Structural Dynamics, 4 (6). 061501.

[img] PDF - Published Version
Restricted to Repository staff only
Available under License CC BY (Attribution).


Official URL: https://edoc.unibas.ch/94253/

Downloads: Statistics Overview


We review several methods for computing kinetic isotope effects in chemical reactions including semiclassical and quantum instanton theory. These methods describe both the quantization of vibrational modes as well as tunneling and are applied to the ⋅H + H 2 and ⋅H + CH 4 reactions. The absolute rate constants computed with the semiclassical instanton method both using on-the-fly electronic structure calculations and fitted potential-energy surfaces are also compared directly with exact quantum dynamics results. The error inherent in the instanton approximation is found to be relatively small and similar in magnitude to that introduced by using fitted surfaces. The kinetic isotope effect computed by the quantum instanton is even more accurate, and although it is computationally more expensive, the efficiency can be improved by path-integral acceleration techniques. We also test a simple approach for designing potential-energy surfaces for the example of proton transfer in malonaldehyde. The tunneling splittings are computed, and although they are found to deviate from experimental results, the ratio of the splitting to that of an isotopically substituted form is in much better agreement. We discuss the strengths and limitations of the potential-energy surface and based on our findings suggest ways in which it can be improved.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Physikalische Chemie (Meuwly)
UniBasel Contributors:Meuwly, Markus
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:AIP Publishing
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
edoc DOI:
Last Modified:17 Apr 2023 07:25
Deposited On:17 Apr 2023 07:25

Repository Staff Only: item control page