Theoretical Chemistry Accounts

, Volume 118, Issue 4, pp 813–826

Symmetry numbers and chemical reaction rates

  • Antonio Fernández-Ramos
  • Benjamin A. Ellingson
  • Rubén Meana-Pañeda
  • Jorge M. C. Marques
  • Donald G. Truhlar
Open Access
Regular Article

Abstract

This article shows how to evaluate rotational symmetry numbers for different molecular configurations and how to apply them to transition state theory. In general, the symmetry number is given by the ratio of the reactant and transition state rotational symmetry numbers. However, special care is advised in the evaluation of symmetry numbers in the following situations: (i) if the reaction is symmetric, (ii) if reactants and/or transition states are chiral, (iii) if the reaction has multiple conformers for reactants and/or transition states and, (iv) if there is an internal rotation of part of the molecular system. All these four situations are treated systematically and analyzed in detail in the present article. We also include a large number of examples to clarify some complicated situations, and in the last section we discuss an example involving an achiral diasteroisomer.

Keywords

Symmetry numbers Chemical reactions Transition state theory Chiral molecules Multiple conformers Internal rotation 

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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Antonio Fernández-Ramos
    • 1
  • Benjamin A. Ellingson
    • 2
  • Rubén Meana-Pañeda
    • 1
  • Jorge M. C. Marques
    • 3
  • Donald G. Truhlar
    • 2
  1. 1.Departamento de Química Física, Facultade de QuímicaUniversidade de Santiago de CompostelaSantiago de CompostelaSpain
  2. 2.Department of Chemistry and Supercomputing InstituteUniversity of MinnesotaMinneapolisUSA
  3. 3.Departamento de QuímicaUniversidade de CoimbraCoimbraPortugal

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