A coarse-grain force field for RDX: Density dependent and energy conserving

Area of Science:

• Materials Science
• Computational Chemistry
• Chemical Engineering

Background:

• Existing coarse-grain models for hexahydro-1,3,5-trinitro-s-triazine (RDX) using force-matching methods exhibit limitations in energy conservation.
• Previous models relied on interpolation schemes for density-dependent forces, leading to poor energy conservation during simulations.

Purpose of the Study:

• To develop an improved, density-dependent, transferable coarse-grain model for RDX.
• To enhance the structural and thermodynamic properties of RDX models.
• To ensure energy conservation in dissipative particle dynamics simulations of RDX.

Main Methods:

• Development of a density-dependent transferable coarse-grain model for RDX.
• Utilized energy-conserving dissipative particle dynamics.
• Employed a multi-objective optimization procedure for structural and thermodynamic properties.
• Incorporated a conservative force field for density dependency.

Main Results:

• The new model accurately predicts the density, structure, pressure-volume isotherm, bulk modulus, and elastic constants of RDX crystals at ambient pressure.
• The model demonstrates transferability to the liquid phase of RDX under melt conditions.
• Achieved improved structural and thermodynamic properties compared to previous models.

Conclusions:

• The developed coarse-grain model offers accurate predictions for RDX crystal properties.
• The model's energy-conserving nature is crucial for reliable simulations.
• Demonstrated successful transferability to liquid-phase RDX, expanding its applicability.