Constant-force approach to discontinuous potentials

TL;DR

This paper introduces a constant-force method to approximate discontinuous hard-core potentials in molecular dynamics, enabling better simulation of thermodynamic properties with improved accuracy over traditional models.

Contribution

The paper presents a novel constant-force approach that replaces discontinuous potentials with linear functions, facilitating standard molecular dynamics simulations of hard-core systems.

Findings

Remarkable agreement in vapor-liquid coexistence densities

Accurate surface tension measurements

Effective approximation of discontinuous potentials

Abstract

Aiming to approach the thermodynamical properties of hard-core systems by standard molecular dynamics simulation, we propose setting a repulsive constant-force for overlapping particles. That is, the discontinuity of the pair potential is replaced by a linear function with a large negative slope. Hence, the core-core repulsion, usually modeled with a power function of distance, yields a large force as soon as the cores slightly overlap. This leads to a quasi-hardcore behavior. The idea is tested for a triangle potential of short range. The results obtained by replica exchange molecular dynamics for several repulsive forces are contrasted with the ones obtained for the discontinuous potential and by means of replica exchange Monte Carlo. We found remarkable agreements for the vapor-liquid coexistence densities as well as for the surface tension.