Homogeneous nucleation in supersaturated vapors of methane, ethane, and carbon dioxide predicted by brute force molecular dynamics

TL;DR

This study uses large-scale molecular dynamics simulations to investigate homogeneous nucleation in supersaturated vapors of methane, ethane, and carbon dioxide, comparing results with classical and size-dependent nucleation theories.

Contribution

It demonstrates the feasibility of simulating nucleation with up to a million particles and compares classical and size-dependent theories against simulation data.

Findings

CNT accurately predicts ethane and CO2 nucleation.

LFK theory better describes methane at low temperatures.

Simulations reach nucleation rates of 10^30/(m^3 s).

Abstract

Molecular dynamics (MD) simulation is applied to the condensation process of supersaturated vapors of methane, ethane, and carbon dioxide. Simulations of systems with up to a million particles were conducted with a massively parallel MD program. This leads to reliable statistics and makes nucleation rates down to the order of 10^30/(m^3 s) accessible to the direct simulation approach. Simulation results are compared to the classical nucleation theory (CNT) as well as the theory of Laaksonen, Ford, and Kulmala (LFK) which introduces a size dependence of the specific surface energy. CNT describes the nucleation of ethane and carbon dioxide excellently over the entire studied temperature range, whereas LFK provides a better approach to methane at low temperatures.