Force Field Optimization and Surface-Induced Cooperative Nucleation in n-Octane Crystallization via Molecular...

Area of Science:

• Materials Science
• Computational Chemistry
• Energy Storage

Background:

• Phase-change materials (PCMs) are crucial for energy storage, requiring accurate atomistic understanding of solid-liquid transitions.
• Modeling n-octane's phase behavior is essential for developing organic PCMs.

Purpose of the Study:

• To optimize force field parameters for n-octane to accurately predict its melting point and phase transition mechanisms.
• To provide molecular-level insights for designing improved organic phase-change materials.

Main Methods:

• Two-dimensional scanning of force field parameters (σ, ε) for n-octane.
• Molecular dynamics simulations to investigate melting point and crystallization pathways.
• Finite-size analysis and comprehensive sensitivity studies.

Main Results:

• Optimized force field parameters reduced the melting point prediction error for n-octane from ~91 K to 1 K.
• Identified a surface-nucleation pathway during crystallization, differing from classical theories.
• Chain orientation within the crystal influences the structure of surface nuclei.

Conclusions:

• Accurate force field parameterization is key for reliable phase-transition modeling of organic PCMs.
• The study offers molecular-level guidance for the rational design of novel organic phase-change materials.
• Findings challenge existing nucleation theories and provide a new framework for PCM research.