Bond Orientational Order Parameters for Classifying Solid-like Clusters in a Lennard-Jones System near Liquid-Solid...

Area of Science:

• Condensed matter physics
• Materials science
• Computational chemistry

Background:

• Characterizing local atomic arrangements in liquids is crucial for understanding phase transitions.
• Existing order parameters may not fully capture the structural nuances of disordered phases.

Purpose of the Study:

• Introduce a novel order parameter, local structure similarity (LSS), to quantify cluster resemblance to crystalline structures.
• Evaluate the effectiveness of LSS in analyzing solid-like clusters in a Lennard-Jones system.
• Compare LSS classification with traditional order parameters (W4, W6) for different cluster types (fcc, hcp, bcc).

Main Methods:

• Developed the LSS order parameter based on bond orientational order complex vectors.
• Calculated LSS by scanning Euler angles between liquid and crystal frames.
• Simulated a Lennard-Jones system using annealing to obtain thermodynamic states.
• Analyzed fcc-like, hcp-like, and bcc-like clusters using LSS and W4/W6 parameters.

Main Results:

• LSS effectively measures the resemblance of liquid clusters to perfect crystals.
• LSS classification aligns well with W4/W6 criteria for fcc-like and hcp-like clusters.
• Discrepancies were observed for bcc-like clusters, where LSS results contradicted W6-based classification.

Conclusions:

• The LSS order parameter provides a robust method for assessing local structural similarity in liquids.
• LSS offers a more refined analysis, particularly for complex structures like bcc.
• Further investigation is warranted for bcc-like cluster classification using LSS.