Direct observation of single Ostwald ripening processes by molecular dynamics simulation

Area of Science:

• * Material science
• * Biophysics
• * Geology
• * Product formulation

Background:

• * Ostwald ripening is a crucial growth mechanism observed across diverse scientific disciplines.
• * Understanding cluster dynamics is key to controlling material properties and system evolution.
• * Previous models often assumed direct contact or bridging for Ostwald ripening to initiate.

Purpose of the Study:

• * To directly observe and analyze Ostwald ripening in argon clusters using molecular dynamics.
• * To investigate the initiation mechanisms of Ostwald ripening, particularly the role of cluster proximity and energy fluctuations.
• * To establish a model system for studying large-time scale ripening phenomena.

Main Methods:

• * Constant energy molecular dynamics simulations were employed.
• * Argon clusters in a vapor phase were simulated starting from a metastable equilibrium.
• * Kinetic energy was added to mimic thermal fluctuations and initiate ripening.

Main Results:

• * Ostwald ripening was observed directly in the simulated argon cluster system.
• * The onset of ripening was not necessarily preceded by close cluster encounters or static density bridges.
• * Ripening initiation was linked to the differing evaporation dynamics of clusters of varying sizes.

Conclusions:

• * Ostwald ripening onset is primarily governed by size-dependent evaporation dynamics, not solely by cluster proximity.
• * Molecular dynamics simulations provide valuable insights into the fundamental mechanisms of Ostwald ripening.
• * The findings offer a refined understanding of cluster growth and evolution in various scientific contexts.