Temperature-dependent potential for the molecular dynamics of the superionic conductor β-PbF2

Area of Science:

• Materials Science
• Computational Physics
• Solid State Chemistry

Background:

• Lead fluoride (PbF2) exhibits complex thermodynamic and structural behaviors, particularly near its superionic transition.
• Accurate modeling of temperature-dependent properties is crucial for understanding PbF2's phase transitions and applications.

Purpose of the Study:

• To investigate the thermodynamic and structural properties of lead fluoride (PbF2) using molecular dynamic (MD) calculations.
• To develop and validate a novel inter-ionic, temperature-dependent potential for PbF2.
• To precisely model the anomalous temperature dependence of the lattice parameter in PbF2.

Main Methods:

• Employed molecular dynamic (MD) simulations with a newly proposed inter-ionic temperature-dependent potential.
• The potential was decomposed into temperature-independent and temperature-dependent components.
• Data fitting was performed in two distinct temperature regions (300–700 K and 700–900 K) to capture phase transition effects.

Main Results:

• The developed potential accurately predicts the linear thermal expansivity and lattice parameter of PbF2 as a function of temperature.
• Successfully modeled the anomalous behavior of the lattice parameter near the superionic transition, a previously unaddressed aspect in MD studies.
• Achieved high precision in calculations, showing excellent agreement with experimental measurements.

Conclusions:

• The proposed temperature-dependent potential is effective for accurately simulating the thermodynamic and structural properties of PbF2.
• This study provides a precise computational method for understanding PbF2's anomalous lattice expansion near its superionic state.
• The findings validate the potential's capability to reproduce experimental observations for lead fluoride.