Molecular dynamic simulations of atom-cluster collision processes.

Area of Science:

• Physical Chemistry
• Computational Physics
• Materials Science

Background:

• Understanding nucleation and growth processes is crucial for various fields, including atmospheric science and materials engineering.
• Atomistic simulations provide a powerful tool to investigate the fundamental dynamics of cluster formation.

Purpose of the Study:

• To investigate monomer-cluster collisions of Lennard-Jones argon atoms.
• To calculate capture probabilities and cluster lifetimes as a function of impact parameter and cluster energy.
• To determine the average lifetime for different cluster sizes and energies.

Main Methods:

• Molecular dynamics simulations were employed.
• Simulations were performed for target cluster sizes ranging from 2 to 20 atoms.
• Capture probabilities and cluster lifetimes were computed, with lifetimes integrated over impact parameters.

Main Results:

• The capture probability of monomers by clusters was calculated.
• Cluster lifetimes were determined as a function of impact parameter and total energy.
• Average lifetimes were obtained by integrating over all impact parameters for each cluster size and energy.
• Small argon aggregates exhibit short average lifetimes relative to collision times, particularly in undersaturated vapor.
• Cluster formation probability significantly decreases when a minimum lifetime criterion is imposed.

Conclusions:

• The stability of small argon clusters is limited under typical collision conditions.
• The supersaturation level of the vapor critically influences the likelihood of new cluster formation.
• These findings have implications for modeling nucleation processes in gases and aerosols.