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Computational Treatments of Peroxy Radicals in Combustion and Atmospheric Reactions

Peroxides (2014)

  1. Keith T. Kuwata

Published Online: 28 APR 2014

DOI: 10.1002/9780470682531.pat0861

Patai's Chemistry of Functional Groups

Patai's Chemistry of Functional Groups

How to Cite

Kuwata, K. T. 2014. Computational Treatments of Peroxy Radicals in Combustion and Atmospheric Reactions. Patai's Chemistry of Functional Groups. 1–50.

Author Information

  1. Department of Chemistry, Macalester College, Saint Paul, MN 55105, USA

Publication History

  1. Published Online: 28 APR 2014

Abstract

Alkylperoxy radicals play critical roles in both combustion and in atmospheric chemistry. This review focuses on what electronic structure calculations, particularly those involving ab initio composite methods and density functional theory, have revealed about the mechanisms of important reactions in combustion and atmospheric systems. The formation of alkylperoxy radicals by addition of O2 to alkyl radicals usually proceeds without an energy barrier, and the barriers that do exist often must be treated by multireference electronic structure methods to be predicted accurately. In contrast, peroxy radical well depths can be predicted accurately by single-reference methods, provided that electron correlation is treated at the CCSD(T) or QCISD(T) level with basis sets containing multiple polarization functions. The composite CBS-QB3 method does particularly well as judged against experimental measurements of carbon-peroxy bond dissociation enthalpies. CBS-QB3 also describes atmospheric reactions of alkylperoxy radicals with HO2 more accurately than the B3LYP method of density functional theory. Finally, the same single-reference methods that proved accurate for peroxy radical well depths can also be employed in accurate statistical rate theory models of the unimolecular reactions involved in low-temperature combustion. Multiple variants of density functional theory have proven considerably less accurate in this regard.

Keywords:

  • alkylperoxy radicals;
  • combustion;
  • atmospheric chemistry;
  • electronic structure theory;
  • quantum chemistry;
  • composite methods;
  • CBS-QB3;
  • B3LYP;
  • density functional theory;
  • basis sets;
  • barrier heights;
  • well depths;
  • HO2 ;
  • unimolecular reactions