The role of fluctuations in the nucleation process.

Area of Science:

• * Physical Chemistry
• * Computational Materials Science
• * Statistical Mechanics

Background:

• * The transition from liquid to solid states is a fundamental self-assembly process with significant practical applications.
• * Understanding the nucleation mechanism is crucial for controlling crystallization.
• * Previous computational methods have faced challenges in accurately simulating crystallization dynamics.

Purpose of the Study:

• * To investigate the crystallization transition in a Lennard-Jones fluid using a novel committor-based enhanced sampling method.
• * To analyze the detailed nucleation mechanism and identify key fluctuations leading to solid phase formation.
• * To compute the nucleation rate and compare it with experimental data and previous theoretical estimates.

Main Methods:

• * Employed a recently developed committor-based enhanced sampling technique.
• * Utilized the variational principle derived from the backward Kolmogorov equation.
• * Analyzed the structure of the transition state ensemble during crystallization.

Main Results:

• * Detected and analyzed critical fluctuations driving the crystallization process.
• * Characterized the transition state ensemble, revealing a disordered interface surrounding a nonspherical solid core.
• * Calculated a nucleation rate that aligns with experimental observations, contrasting with earlier computational predictions.

Conclusions:

• * The committor-based enhanced sampling method provides a powerful tool for studying complex phase transitions.
• * The nucleation mechanism involves intricate transition states with unique interfacial properties.
• * The computed nucleation rate offers a more accurate representation of experimental reality compared to previous estimates.