Analyzing multistep homogeneous nucleation in vapor-to-solid transitions using molecular dynamics simulations

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Physics

Background:

• Understanding vapor-to-solid transitions is crucial for materials synthesis and atmospheric science.
• Homogeneous nucleation processes are fundamental to phase transitions but remain complex to model.
• Previous studies often focused on simpler nucleation models, lacking detailed insights into multistep processes.

Purpose of the Study:

• To investigate multistep homogeneous nucleation during vapor-to-solid transitions using molecular dynamics simulations.
• To analyze the crystallization behavior of supercooled liquid nanoclusters.
• To characterize the structural properties and mass changes of clusters during phase transition.

Main Methods:

• Molecular dynamics (MD) simulations using Lennard-Jones molecules.
• Long NVE (constant volume, energy, and number of molecules) ensemble simulations.
• Analysis of cluster growth, crystallization, mass loss, and structural evolution.

Main Results:

• Observed crystallization in supercooled nanoclusters exceeding a critical size (approx. 800 molecules).
• Identified a 2-5% mass loss during crystallization due to evaporation, counteracting latent heat.
• Characterized the formation of metastable crystal structures (icosahedral, decahedral, fcc-rich, hcp-rich) coexisting within clusters.

Conclusions:

• Multistep nucleation is a prevalent initial stage in vapor-to-solid condensation.
• Evaporation plays a stabilizing role during low-temperature crystallization of nanoclusters.
• The complex, metastable structures formed highlight the intricate nature of nanoscale solidification.