Violation of microscopic reversibility and the use of reverse quais-classical trajectories for calculating reaction cross sections

Joel M. Bowman, George C Schatz, Aron Kupperman

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39 Citations (Scopus)


In order to calculate the transition probabilities (or cross sections) for reactive collisions, such as A + BC(ν, j)→ AB(ν′, j) + C, using the quasi-classical trajectory method, one quantizes the internal energy of the reagents and in addition adopts some algorithm for calculating the internal quantum numbers of the products. A serious consequence of this procedure is that the quasi-classical results do not obey microscopic reversibility. It is shown that for the collinear F + H2(ν = 0) → FH(ν = 2, 3)+ H reaction (and its D2 counterpart), the quasi-classical trajectory probabilities for the reverse reaction not only differ substantially from the forward ones but in general are in much better agreement with accurate quantum calculations. A similar situation was found for the collinear H + H2(0) → H2(1) + H reaction. We suggest that in doing quasi-classical calculations, the reverse of the process of interest should also be considered. Comparison of forward and reverse quasi-classical collinear calculations with accurate collinear quantum results could give an indication of whether forward or reverse calculations should be used for the three-dimensional case.

Original languageEnglish
Pages (from-to)378-380
Number of pages3
JournalChemical Physics Letters
Issue number3
Publication statusPublished - Feb 1 1974


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Condensed Matter Physics
  • Atomic and Molecular Physics, and Optics
  • Surfaces and Interfaces

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