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Title: A comparative study of different methods for calculating electronic transition rates

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [1]
  1. Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
  2. Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA, Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, USA
  3. Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1377138
Grant/Contract Number:
SC0016501
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 148; Journal Issue: 10; Related Information: CHORUS Timestamp: 2018-02-14 15:33:05; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Kananenka, Alexei A., Sun, Xiang, Schubert, Alexander, Dunietz, Barry D., and Geva, Eitan. A comparative study of different methods for calculating electronic transition rates. United States: N. p., 2018. Web. doi:10.1063/1.4989509.
Kananenka, Alexei A., Sun, Xiang, Schubert, Alexander, Dunietz, Barry D., & Geva, Eitan. A comparative study of different methods for calculating electronic transition rates. United States. doi:10.1063/1.4989509.
Kananenka, Alexei A., Sun, Xiang, Schubert, Alexander, Dunietz, Barry D., and Geva, Eitan. 2018. "A comparative study of different methods for calculating electronic transition rates". United States. doi:10.1063/1.4989509.
@article{osti_1377138,
title = {A comparative study of different methods for calculating electronic transition rates},
author = {Kananenka, Alexei A. and Sun, Xiang and Schubert, Alexander and Dunietz, Barry D. and Geva, Eitan},
abstractNote = {},
doi = {10.1063/1.4989509},
journal = {Journal of Chemical Physics},
number = 10,
volume = 148,
place = {United States},
year = 2018,
month = 3
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on August 29, 2018
Publisher's Accepted Manuscript

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  • In many cases, variational transition states for a chemical reaction are significantly displaced from a saddle point because of zero-point and entropic effects that depend on the reaction coordinate. Such displacements are often controlled by the competition between the potential energy along the minimum-energy reaction path and the energy requirements of one or more vibrational modes whose frequencies show a large variation along the reaction path. In calculating reaction rates from potential-energy functions we need to take account of these factors and---especially at lower temperatures---to include tunneling contributions, which also depend on the variation of vibrational frequencies along a reactionmore » path. To include these effects requires more information about the activated complex region of the potential-energy surface than is required for conventional transition-state theory. In the present article we show how the vibrational and entropic effects of variational transition-state theory and the effective potentials and effective masses needed to calculate tunneling probabilities can be estimated with a minimum of electronic structure information, thereby allowing their computation at a higher level of theory than would otherwise be possible. As examples, we consider the reactions OH+H{sub 2}, CH{sub 3}+H{sub 2}, and Cl+CH{sub 4} and some of their isotopic analogs. We find for Cl+CH{sub 4}{r arrow}HCl+CH{sub 3} that the reaction rate is greatly enhanced by tunneling under conditions of interest for atmospheric chemistry.« less
  • Three methods of measuring SSSRn concentration in homes were compared. In 91 dwellings, measurements were made with thermoluminescence dosimeters (TLDs) for two weeks during the winter, with alpha track Track Etch type SF dosimeters (ATDs) for six months during the heating season and for one year. There was a high correlation between the TLD and the six-month ATD values (r = .83) and between the six-month and the one-year ATD values (r = .80). On the average, however, the arithmetic and geometric means of the ATD (six-month) values were approximately 50 Bq m-3 higher than the TLD values (p lessmore » than .0001). The six-month ATD values also were, on the average, approximately eight percent higher than the one-year values. This difference is probably caused by decreased ventilation during the colder part of the year. The results indicate that the measurement methods under study may be of value for exposure assessments in epidemiologic studies, but also that estimates of risk per unit radiation exposure should be interpreted with caution.« less
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