Comparative study on methodology in molecular dynamics simulation of nucleation.

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Computational Chemistry

Background:

• Gas-liquid nucleation is a fundamental process in physical chemistry.
• Accurate simulation of nucleation requires reliable temperature control and rate determination methods.
• Previous studies have utilized various thermostats and nucleation rate calculation techniques.

Purpose of the Study:

• To compare the effectiveness of the Berendsen and Andersen thermostats in simulating gas-liquid nucleation.
• To evaluate different methods for obtaining nucleation rates from simulation data.
• To analyze the behavior of atomic and cluster velocities during nucleation.

Main Methods:

• Simulations of 1000 Lennard-Jones atoms using the Berendsen and Andersen thermostats.
• Analysis of atomic and cluster velocities using the Maxwell velocity distribution.
• Extraction of nucleation rates via direct observation and the Yasuoka-Matsumoto method.

Main Results:

• The Berendsen thermostat struggled to control temperature for clusters exceeding critical size.
• Both thermostats yielded velocities consistent with the Maxwell distribution for individual atoms and small clusters.
• The Andersen thermostat produced nucleation rates approximately twice as high as the Berendsen thermostat.
• The Yasuoka-Matsumoto method yielded nucleation rates three times higher than direct observation.

Conclusions:

• The Andersen thermostat is more suitable for simulating gas-liquid nucleation compared to the Berendsen thermostat.
• The choice of nucleation rate calculation method significantly impacts the obtained results.
• Maxwell velocity distribution accurately describes particle velocities in the simulated system.