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11:59
High-speed Particle Image Velocimetry Near Surfaces
Published on: June 24, 2013
Microcanonical rates, gap times, and phase space dividing surfaces
Gregory S Ezra1, Holger Waalkens, Stephen Wiggins
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA. gse1@cornell.edu
The Journal of Chemical Physics
|May 2, 2009
Summary
This study revisits Thiele
Area of Science:
- Chemical Kinetics
- Theoretical Chemistry
- Statistical Mechanics
Background:
- Classical unimolecular reaction rates.
- Phase space formulation of transition state theory for multidimensional systems.
Purpose of the Study:
- Revisit Thiele's approach to unimolecular reaction rates.
- Analyze gap time and reactant lifetime distributions for HCN isomerization.
- Compare statistical estimates with numerically determined rates.
Main Methods:
- Phase space formulation of transition state theory.
- Analysis of gap time and reactant lifetime distributions.
- Comparison of theoretical estimates with numerical simulations.
Main Results:
- Identified algebraic (power law) and exponential decay regimes for HCN isomerization.
- Correcting RRKM estimates for trapped trajectories led to overestimation of isomerization rate.
- Uncorrected RRKM estimates were reasonably accurate due to compensating trapping mechanisms.
Conclusions:
- Complete trajectory ensembles attain system phase space symmetry rapidly.
- Statistical product branching ratio (1:1) observed after short timescales.
- Nonexponential decay and nonstatistical behavior observed at intermediate times, paralleling organic molecule reactions.
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