Nonstatistical reaction dynamics

Bhumika Jayee, William L. Hase

Research output: Contribution to journalReview articlepeer-review

15 Scopus citations


Nonstatistical dynamics is important for many chemical reactions. The Rice-Ramsperger-Kassel-Marcus (RRKM) theory of unimolecular kinetics assumes a reactant molecule maintains a statistical microcanonical ensemble of vibrational states during its dissociation so that its unimolecular dynamics are time independent. Such dynamics results when the reactant's atomic motion is chaotic or irregular. Intrinsic non-RRKM dynamics occurs when part of the reactant's phase space consists of quasiperiodic/regular motion and a bottleneck exists, so that the unimolecular rate constant is time dependent. Nonrandom excitation of a molecule may result in short-time apparent non-RRKM dynamics. For rotational activation, the 2J + 1 K levels for a particular J may be highly mixed, making K an active degree of freedom, or K may be a good quantum number and an adiabatic degree of freedom. Nonstatistical dynamics is often important for bimolecular reactions and their intermediates and for product-energy partitioning of bimolecular and unimolecular reactions. Post-transition state dynamics is often highly complex and nonstatistical.

Original languageEnglish
Pages (from-to)289-313
Number of pages25
JournalAnnual Review of Physical Chemistry
StatePublished - Apr 20 2020


  • SN2 reaction dynamics
  • active rotation
  • adiabatic rotation
  • bimolecular reactions
  • non-RRKM unimolecular dynamics
  • nonintrinsic reaction coordinate dynamics
  • nonstatistical reaction dynamics
  • phase space dynamics
  • post-transition state dynamics
  • product energy partitioning
  • reaction intermediates
  • rotational/vibrational coupling


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