A simple and accurate method to determine fluid-crystal phase boundaries from direct coexistence simulations

Area of Science:

• Computational physics
• Materials science
• Statistical mechanics

Background:

• Determining phase boundaries computationally is crucial for materials science.
• Direct coexistence simulations are effective for fluid-fluid systems but challenging for fluid-crystal transitions due to strain issues.
• Existing methods for fluid-crystal phase boundaries often involve complex free-energy calculations.

Purpose of the Study:

• To present a simplified adaptation of the direct coexistence method for accurate fluid-crystal phase boundary prediction.
• To demonstrate the method's applicability across various systems, including hard spheres and screened Coulomb potentials.
• To provide an accessible and efficient alternative to traditional free-energy based methods.

Main Methods:

• Adaptation of the direct coexistence simulation method.
• Explicit simulation of direct coexistence between fluid and crystal phases.
• Testing the method on hard spheres, screened Coulomb potential, and a 2D patchy-particle model.

Main Results:

• The adapted direct coexistence method yields highly accurate predictions of fluid-crystal coexistence conditions.
• Excellent agreement was found between this method and more cumbersome free-energy calculation methods.
• The method successfully resolved the minute free-energy difference between FCC and HCP crystal phases of hard spheres.

Conclusions:

• The presented direct coexistence method is a simple yet accurate approach for determining fluid-crystal phase boundaries.
• This method overcomes limitations of traditional direct coexistence simulations for crystalline phases.
• Its ease of implementation makes it a valuable alternative for precise phase boundary determination in various simulation packages.