Constant pressure and temperature discrete-time Langevin molecular dynamics

Area of Science:

• Computational Physics
• Materials Science
• Statistical Mechanics

Background:

• Accurate control of temperature and pressure is crucial for molecular dynamics (MD) simulations.
• Existing methods may exhibit sensitivity to the chosen time step, affecting statistical reliability.
• Previous work established a stochastic thermostat for correct configurational sampling.

Purpose of the Study:

• To present a novel, improved method for simultaneous temperature and pressure control in MD simulations.
• To develop discrete-time equations of motion for particle dynamics and system volume.
• To achieve pressure control that is independent of the numerical time step.

Main Methods:

• Extension of a previously developed stochastic thermostat.
• Formulation of discrete-time equations for particle dynamics and system volume.
• Numerical simulations of a 1D particle chain and 3D Lennard-Jones systems (solid and liquid phases).

Main Results:

• The new method demonstrates accurate and robust statistical averages and fluctuations.
• Performance is validated against benchmark results for a 1D chain.
• Comparison with the Kolb and Dünweg method shows comparable or improved accuracy.
• The method is insensitive to the chosen simulation time step.

Conclusions:

• The presented method offers a simple, practical, and efficient approach for simultaneous temperature and pressure control in MD.
• It ensures accurate statistical sampling and reliable thermodynamic properties.
• The time-step independence makes it a robust tool for various simulation scenarios.