Transition state theory approach to polymer escape from a one dimensional potential well

Area of Science:

• Polymer Physics
• Chemical Physics
• Computational Chemistry

Background:

• Investigating polymer dynamics in complex potentials is crucial for understanding material properties.
• The Kramers-Langer estimate, a common method, can be inaccurate for long polymers due to diffusive dynamics.
• Accurate calculation of escape rates is essential for predicting polymer behavior in various environments.

Purpose of the Study:

• To calculate the escape rate of an ideal bead-spring polymer in a symmetric double-well potential.
• To compare the accuracy of transition state theory (TST) with direct dynamical simulations.
• To assess the efficiency of TST for predicting polymer escape rates across different polymer lengths and coupling constants.

Main Methods:

• Utilizing transition state theory (TST) with dynamical corrections.
• Performing direct molecular dynamics (MD) simulations for comparison.
• Analyzing short-time trajectories initiated at the transition state for TST corrections.

Main Results:

• TST with dynamical corrections provides rate constant estimates within a factor of two of MD simulations.
• The accuracy holds over a wide range of bead coupling constants and polymer lengths.
• The Kramers-Langer estimate proves inadequate for long polymers where dynamics become diffusive.

Conclusions:

• Dynamically corrected TST is a computationally efficient and accurate method for calculating polymer escape rates.
• This approach overcomes limitations of traditional methods for long polymers in double-well potentials.
• The TST method's computational cost is independent of the escape rate, offering significant advantages.