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Exploring the dynamics of dimer crossing over a Kramers type potential
Mesfin Asfaw1, Yohannes Shiferaw
1Department of Physics and Astronomy, California State University Northridge, California 91330, USA. mesfin.taye@csun.edu
The Journal of Chemical Physics
|January 21, 2012
Summary
Dimer escape rates across barriers show complex behavior. Cooperativity initially enhances crossing, but too much coupling hinders it, revealing an optimal spring constant for efficient barrier traversal.
Area of Science:
- Chemical Physics
- Statistical Mechanics
- Biophysics
Background:
- Understanding molecular dynamics and reaction rates is crucial in various scientific fields.
- Dimer systems offer a simplified yet informative model for studying cooperative effects in barrier crossing.
Purpose of the Study:
- To investigate the escape rate of a dimer across a potential barrier.
- To analyze the influence of coupling strength on the dimer's barrier crossing dynamics.
- To explore the system's response to external periodic signals.
Main Methods:
- Analytical calculations to model the escape rate.
- Numerical simulations to complement analytical findings.
- Adiabatic elimination to analyze the large coupling strength regime.
Main Results:
- For small coupling strength (k), escape rate increases with k, indicating enhanced crossing due to cooperativity.
- In the large coupling strength limit, escape rate decreases with k.
- The escape rate is a non-monotonic function of coupling strength, exhibiting a peak at an optimal value.
- A weak periodic signal can lead to pronounced system response and rapid dimer transport at a specific coupling strength.
Conclusions:
- Dimer escape rate is non-monotonically dependent on coupling strength, with an optimal value for efficient barrier crossing.
- Cooperativity plays a dual role, enhancing crossing at low coupling but potentially hindering it at high coupling.
- The system demonstrates tunable transport properties, responding strongly to periodic signals at optimal coupling.
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