Communication: Truncated non-bonded potentials can yield unphysical behavior in molecular dynamics simulations of interfaces

TL;DR

This paper reveals that truncating non-bonded potentials in molecular dynamics simulations can cause unphysical behaviors, such as altering the nature of wetting transitions, which are not mitigated by common correction methods.

Contribution

It demonstrates that common truncation practices can lead to significant unphysical effects in simulations of interfaces, challenging current assumptions.

Findings

Truncation can change wetting transition from continuous to first order.

Force corrections do not prevent unphysical behavior.

Unphysical effects are significant and not fully correctable.

Abstract

Non-bonded potentials are included in most force fields and therefore widely used in classical molecular dynamics simulations of materials and interfacial phenomena. It is commonplace to truncate these potentials for computational efficiency based on the assumption that errors are negligible for reasonable cutoffs or compensated for by adjusting other interaction parameters. Arising from a metadynamics study of the wetting transition of water on a solid substrate, we find that the influence of the cutoff is unexpectedly strong and can change the character of the wetting transition from continuous to first order by creating artificial metastable wetting states. Common cutoff corrections such as the use of a force switching function, a shifted potential, or a shifted force do not avoid this. Such a qualitative difference urges caution and suggests that using truncated non-bonded potentials can induce unphysical behavior that cannot be fully accounted for by adjusting other interaction parameters.