Informal Statistical Physics Seminar

Date
Tue, Dec 6, 2022 1:00 pm - 2:30 pm
Location
https://go.umd.edu/statphys_zoom

Description

Speaker: Professor Peter Bolhuis, University of Amsterdam

Title: A Maximum Caliber Approach for Tuning Molecular Kinetics


Abstract: 
Empirical force fields used in Molecular Dynamics simulations of complex biomolecules and materials are often approximate. Statistical methods based on the maximum-entropy principle are able to increase the accuracy of “structural and thermodynamical ensembles” obtained by such molecular dynamics simulations through incorporating experimental information. One would like to go even further, by obtaining ‘kinetic ensembles’, comprising the structures of the different states of a molecular system, their populations and their interconversion rates. However, up to recently there was no systematic way to incorporate experimental dynamical and kinetic information into molecular dynamics simulations. We developed a method of imposing known rate constants (and other dynamical observables) as constraints in molecular dynamics simulations, based on a combination of the maximum-entropy (MaxEnt) and maximum-caliber principles (MaxCal) [1]. Starting from an existing ensemble of (rare event) dynamical trajectories or paths, e.g. obtained from transition path sampling, each path is reweighted in order to match the calculated and experimental interconversion rates of a molecular transition of interest, while minimally perturbing the prior path distribution. This kinetically corrected ensemble of trajectories leads to improved structure, kinetics, thermodynamics, free energy landscapes, as well as mechanistic insights that may not be readily evident directly from the experiments. Finally, the MaxCal approach can also be used to fine-tune the molecular force fields themselves, and might provide an efficient means for designing kinetic behavior [2].

 

[1] Z. F. Brotzakis, M. Vendruscolo, and P. G. Bolhuis, Proc. Natl. Acad. Sci. 118, (2020).

[2] P. G. Bolhuis, Z. F. Brotzakis, and B. G. Keller, arXiv:2207.04558 (2022).