Faster strain fluctuation methods through partial volume updates

TL;DR

This paper introduces a Monte Carlo algorithm that efficiently samples elastic fluctuations in heterogeneous systems by deforming only subvolumes, overcoming limitations of traditional methods that struggle with stiff regions.

Contribution

The authors develop and detail a novel 'slice move' Monte Carlo method that allows for localized deformations, improving sampling efficiency in heterogeneous elastic systems.

Findings

Efficient sampling of fluctuations in heterogeneous systems.

Successful application to a cross-linked polymer network.

Overcomes restrictions of traditional homogeneous deformation methods.

Abstract

Elastic systems that are spatially heterogeneous in their mechanical response pose special challenges for molecular simulations. Standard methods for sampling thermal fluctuations of a system's size and shape proceed through a series of homogeneous deformations, whose magnitudes can be severely restricted by its stiffest parts. Here we present a Monte Carlo algorithm designed to circumvent this difficulty, which can be prohibitive in many systems of modern interest. By deforming randomly selected subvolumes alone, it naturally distributes the amplitude of spontaneous elastic fluctuations according to intrinsic heterogeneity. We describe in detail implementations of such "slice moves" that are consistent with detailed balance. Their practical application is illustrated for a random network of cross-linked polymers.