The Kob-Andersen model crystal structure: Genetic algorithms vs spontaneous crystallization.

Area of Science:

• Condensed Matter Physics
• Computational Materials Science

Background:

• The Kob-Andersen mixture is a model system used to study phase behavior in binary mixtures.
• Understanding the crystal structures formed by such mixtures is crucial for predicting their macroscopic properties.

Purpose of the Study:

• To computationally determine the stable and metastable crystal structures of the Kob-Andersen mixture across various molar fractions.
• To assess the stability of these identified structures at finite temperatures.

Main Methods:

• Genetic algorithm calculations were employed to explore the potential energy surface and identify low-energy crystal structures.
• Molecular dynamics simulations were utilized to investigate spontaneous crystallization from a liquid state.
• Stability analysis at finite temperatures was performed to validate the predicted structures.

Main Results:

• Stable crystal structures corresponding to compositions ABn, where n = 2, 3, and 4, were identified.
• Metastable structures with compositions AB0.4 and AB0.58 were also found.
• The stability of the identified structures at finite temperatures was confirmed.

Conclusions:

• The Kob-Andersen mixture exhibits a rich phase diagram with multiple stable and metastable crystalline phases.
• Computational methods like genetic algorithms and molecular dynamics are effective tools for predicting crystal structures in complex mixtures.