Nonequilibrium molecular dynamics method based on coarse-graining formalism: Application to a nonuniform temperature...

Area of Science:

• Computational Physics
• Materials Science
• Statistical Mechanics

Background:

• Simulating nonequilibrium systems is crucial for understanding material properties under dynamic conditions.
• Existing methods for generating nonequilibrium states can lack flexibility and precise control.
• Developing advanced simulation techniques is essential for exploring complex physical phenomena.

Purpose of the Study:

• To propose a novel nonequilibrium molecular dynamics (NEMD) method for flexible generation of nonequilibrium states.
• To enable precise control over coarse-grained physical quantities within molecular dynamics simulations.
• To investigate the creation of nonuniform temperature fields and analyze their characteristics.

Main Methods:

• Implementation of virtual points within the simulation box.
• Application of Gauss's principle of least constraint to coarse-grained quantities.
• Calculation of weights using the Moore-Penrose pseudoinverse of a shape function matrix derived from particle configurations.
• Constraining coarse-grained kinetic energy to induce specific nonequilibrium conditions.

Main Results:

• Successful generation of nonequilibrium states with controlled coarse-grained physical quantities.
• Demonstration of the ability to produce nonuniform temperature fields in the system.
• Observation that the temperature profile in a nonequilibrium steady state is dependent on the shape function matrix construction.
• Finding that local temperature matches coarse-grained temperature with higher-order interpolation in the shape function matrix.

Conclusions:

• The proposed NEMD method offers a flexible and effective approach for simulating nonequilibrium systems.
• The technique allows for the creation of specific temperature gradients, advancing the study of thermal transport.
• Higher-order interpolation in shape function construction ensures accurate local temperature representation, validating the method's precision.