Efficient Computation of Entropy and Other Thermodynamic Properties for Two-Dimensional Systems Using Two-Phase...

Area of Science:

• Thermodynamics
• Computational Chemistry
• Materials Science

Background:

• The two-phase thermodynamic (2PT) model is established for calculating absolute entropy in 3D molecular systems.
• Calculating thermodynamic properties for 2D systems presents unique challenges due to differences in fluid behavior.

Purpose of the Study:

• To adapt and validate the 2PT method for calculating entropy and free energy in two-dimensional (2D) molecular systems.
• To provide an efficient computational approach for assessing thermodynamic properties in 2D simulations.

Main Methods:

• Modified the fluidicity concept in the 2PT model to decompose vibrational density of states (DoS) into solid-like (quantum statistics) and gas-like (hard-disk fluid) components.
• Applied the revised 2PT method to molecular dynamics (MD) simulations of a 2D Lennard-Jones fluid.
• Validated the method by comparing computed thermodynamic properties with those from the equation of state.

Main Results:

• The revised 2PT method accurately calculates entropy and free energy for 2D systems.
• Excellent agreement was observed between 2PT results and the equation of state for a 2D Lennard-Jones fluid across various densities and temperatures.
• The method requires short MD trajectories (less than 50 ps) for efficient calculation.

Conclusions:

• The adapted 2PT method offers a robust and efficient approach for determining thermodynamic properties of 2D molecular systems.
• This computational tool can significantly aid research in 2D materials and systems.
• The revised model addresses the specific fluid dynamics of 2D systems, enhancing predictive accuracy.