Grand canonical steady-state simulation of nucleation

TL;DR

This paper introduces a steady-state simulation method using grand canonical molecular dynamics with a Maxwell's demon variant to accurately measure nucleation rates in metastable fluids, validated against traditional methods.

Contribution

It presents a novel steady-state simulation approach for nucleation using GCMD and McDonald's demon, enabling precise measurement of nucleation rates near the spinodal.

Findings

Nucleation rates are accurately obtained over arbitrary timespans.

Results agree with non-equilibrium MD simulations.

Classical nucleation theory underpredicts nucleation rates by two orders of magnitude.

Abstract

Grand canonical molecular dynamics (GCMD) is applied to the nucleation process in a metastable phase near the spinodal, where nucleation occurs almost instantaneously and is limited to a very short time interval. With a variant of Maxwell's demon, proposed by McDonald [Am. J. Phys. 31: 31 (1963)], all nuclei exceeding a specified size are removed. In such a steady-state simulation, the nucleation process is sampled over an arbitrary timespan and all properties of the metastable state, including the nucleation rate, can be obtained with an increased precision. As an example, a series of GCMD simulations with McDonald's demon is carried out for homogeneous vapor to liquid nucleation of the truncated-shifted Lennard-Jones (tsLJ) fluid, covering the entire relevant temperature range. The results are in agreement with direct non-equilibrium MD simulation in the canonical ensemble. It is confirmed for supersaturated vapors of the tsLJ fluid that the classical nucleation theory underpredicts the nucleation rate by two orders of magnitude.