Speaker
Roberto Meloni
(MI)
Description
The description of the dynamics of a complex, high-dimensional system in terms of a low-dimensional set of collective variables (CVs) Ys can be fruitful if the low dimensional representation satisfies a Langevin equation, where drift and diffusion coefficients depend only on the value of Y, but not on the microscopic conformation on which Y has been calculated.
We present here a computational scheme to evaluate whether a given CV Y possess such a property or, on the contrary, whether the drift and diffusion coefficients take different values at distinct conformations, despite Y being equal.
The algorithm is based on the framework of finite-difference Langevin-equation, similar to that used for molecular-dynamics simulations. It allows one to calculate the associated drift and diffusion coefficients in any points of the full-dimensional system. In this way, one can calculate the distribution of drift and diffusion coefficients in an ensemble of microscopic conformations at the same value of Y. The width of this distribution indicates to which extent the dynamics of Y is described by a simple Langevin equation.
Using a simple protein model, we show that collective variables often used to describe biopolymers display a non-negligible width, both in the drift and in the diffusion coefficients.
Primary authors
Dr
Carlo Camilloni
(Department of Chemistry and Institute for Advanced Study, Technische Universität München)
Guido Tiana
(MI)
Roberto Meloni
(MI)
