The flux-flux correlation function for anharmonic barriers

Arseni Goussev, Roman Schubert, Holger Waalkens, Stephen Wiggins*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The flux-flux correlation function formalism is a standard and widely used approach for the computation of reaction rates. In this paper we introduce a method to compute the classical and quantum flux-flux correlation functions for anharmonic barriers essentially analytically through the use of the classical and quantum normal forms. In the quantum case we show that for a general f degree-of-freedom system having an index one saddle the quantum normal form reduces the computation of the flux-flux correlation function to that of an effective one-dimensional anharmonic barrier. The example of the computation of the quantum flux-flux correlation function for a fourth order anharmonic barrier is worked out in detail, and we present an analytical expression for the quantum mechanical microcanonical flux-flux correlation function. We then give a discussion of the short-time and harmonic limits.

Original languageEnglish
Article number244113
JournalJournal of Chemical Physics
Issue number24
Publication statusPublished - 28 Dec 2010


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