
Open access
Date
2019-10-14Type
- Journal Article
Citations
Cited 12 times in
Web of Science
Cited 9 times in
Scopus
ETH Bibliography
yes
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Abstract
We explore the relation between the quantum and semiclassical instanton approximations for the reaction rate constant. From the quantum
instanton expression, we analyze the contributions to the rate constant in terms of minimum-action paths and find that two such paths
dominate the expression. For symmetric barriers, these two paths join together to describe the semiclassical instanton periodic orbit. However,
for asymmetric barriers, one of the two paths takes an unphysically low energy and dominates the expression, leading to order-of-magnitude
errors in the rate predictions. Nevertheless, semiclassical instanton theory remains accurate. We conclude that semiclassical instanton theory
can be obtained directly from the semiclassical limit of the quantum instanton for symmetric systems. We suggest a modification of the
quantum instanton approach which avoids sampling the spurious path and thus has a stronger connection to semiclassical instanton theory,
giving numerically accurate predictions even for very asymmetric systems in the low temperature limit. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000370134Publication status
publishedExternal links
Journal / series
The Journal of Chemical PhysicsVolume
Pages / Article No.
Publisher
AIP PublishingOrganisational unit
09602 - Richardson, Jeremy / Richardson, Jeremy
Related publications and datasets
Is referenced by: http://hdl.handle.net/20.500.11850/382433
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Show all metadata
Citations
Cited 12 times in
Web of Science
Cited 9 times in
Scopus
ETH Bibliography
yes
Altmetrics