How accurate is the Rice–Ramsperger–Kassel–Marcus theory? The case of H+3

The classical Rice–Ramsperger–Kassel–Marcus formula is tested at an accuracy level of a few percent by comparing results of numerical phase space integration with lifetimes deduced from trajectory calculations. The test object is HD+2; the calculation has been done for total energies of 0.5, 1.0, an...

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Veröffentlicht in:The Journal of chemical physics 1994-09, Vol.101 (6), p.4750-4758
Hauptverfasser: Berblinger, Michael, Schlier, Christoph
Format: Artikel
Sprache:eng
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Zusammenfassung:The classical Rice–Ramsperger–Kassel–Marcus formula is tested at an accuracy level of a few percent by comparing results of numerical phase space integration with lifetimes deduced from trajectory calculations. The test object is HD+2; the calculation has been done for total energies of 0.5, 1.0, and 1.5 eV above dissociation, and for total angular momenta of 0–60ℏ. Presupposing that the trajectory calculations show the true classical dynamics, we find systematic deviations of up to 40% of the RRKM results. They can be fully explained by the influence of ‘‘direct trajectories,’’ a special kind of nonergodic behavior of the system. After correction for this phenomenon, both methods agree to within the accuracy of the calculations, which is about 3%. We also verified that the discrepancy vanishes when the energy approaches the dissociation energy.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.467397