Direct calculation of the solid-liquid Gibbs free energy difference in a single equilibrium simulation

Area of Science:

• Computational condensed matter physics
• Thermodynamics
• Materials science

Background:

• Calculating phase diagrams is crucial for understanding material properties.
• Accurate determination of Gibbs free energy difference between phases is essential.
• Existing methods may have limitations in efficiency or precision.

Purpose of the Study:

• To detail the interface pinning (IP) method for calculating Gibbs free energy differences.
• To demonstrate the efficiency and precision of the IP method.
• To investigate the application of the IP method to the Lennard-Jones model.

Main Methods:

• Utilizing a single equilibrium simulation with a harmonic biasing field.
• Applying the interface pinning (IP) method.
• Combining the IP method with the Newton-Raphson root-finding technique.
• Investigating statistical and systematic errors.

Main Results:

• The interface pinning (IP) method allows Gibbs free energy difference calculation in one simulation.
• Efficient and high-precision computation of coexistence lines is achieved when IP is combined with Newton-Raphson.
• The Lennard-Jones model was successfully used as a test system.
• The high-pressure temperature-density coexistence region was mapped using isomorphs.

Conclusions:

• The interface pinning method is an efficient and precise tool for phase diagram computation.
• The IP method offers advantages for calculating phase equilibria in condensed matter systems.
• Further investigation into the method's advantages and drawbacks is warranted.