Molecular dynamics simulations of AP/HMX composite with a modified force field

Area of Science:

• Computational Chemistry
• Materials Science
• Chemical Engineering

Background:

• Ammonium perchlorate (AP) is a key component in solid propellants.
• Understanding the behavior of AP/HMX composites is crucial for propellant safety and performance.
• Existing computational models require refinement for accurate simulation of energetic materials.

Purpose of the Study:

• To develop and validate an all-atom force field for ammonium perchlorate (AP).
• To investigate the molecular dynamics of AP/HMX composites at varying temperatures.
• To establish a criterion for predicting the sensitivity of energetic composites.

Main Methods:

• Development of a modified pcff force field for AP.
• All-atom molecular dynamics (MD) simulations of AP/HMX composites.
• Analysis of binding energies, thermal expansion coefficients, and HMX trigger bond lengths.

Main Results:

• The modified force field accurately reproduces AP structural parameters.
• Binding energies of AP/HMX composites show a temperature-dependent trend, peaking at 245K.
• The volume thermal expansion coefficient was derived from temperature-dependent volume changes.
• Maximal N-NO(2) bond lengths in HMX increase with temperature.

Conclusions:

• The developed force field provides a reliable tool for simulating AP-based systems.
• Trigger bond length in HMX can serve as an indicator of energetic composite sensitivity.
• Temperature significantly influences the structural and energetic properties of AP/HMX composites.