Analysis of Transition State Theory Rates upon Spatial Coarse-Graining

TL;DR

This paper evaluates how well coarse-grained molecular dynamics methods reproduce transition state theory rates compared to fully atomistic models, providing analytical and numerical insights into their accuracy and guiding their application.

Contribution

It offers a detailed analysis of TST rate accuracy in CGMD methods, including error sources and criteria for selecting degrees of freedom, supported by both theoretical and numerical results.

Findings

CGMD can approximate atomistic TST rates with quantifiable errors

Error analysis identifies key factors influencing rate accuracy

Numerical simulations validate analytical predictions for a 1-D chain

Abstract

Spatial multiscale methods have established themselves as useful tools for extending the length scales accessible by conventional statics (i.e., zero temperature molecular dynamics). Recently, extensions of these methods, such as the finite-temperature quasicontinuum (hot-QC) or Coarse-Grained Molecular Dynamics (CGMD) methods, have allowed for multiscale molecular dynamics simulations at finite temperature. Here, we assess the quality of the long-time dynamics these methods generate by considering canonical transition rates. Specifically, we analyze the transition state theory (TST) rates in CGMD and compare them to the corresponding TST rate of the fully atomistic system. The ability of such an approach to reliably reproduce the TST rate is verified through a relative error analysis, which is then used to highlight the major contributions to the error and guide the choice of degrees of freedom. Finally, our analytical results are compared with numerical simulations for the case of a 1-D chain.