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New Insights into Thermal Transport in ε-CL-20 Revealed by Machine-Learned Potentials and Mode-Projection Analysis
Yilin Fang1, Weiyi Li1, Guiyun Hang1
1Rocket Force University of Engineering, Xi'an 710025, People's Republic of China.
The Journal of Physical Chemistry. A
|May 26, 2026
Summary
Thermal conductivity in energetic crystals like ε-CL-20 is key for safety. We found heat conduction degradation and reaction initiation are linked through anharmonic coupling, impacting crystal stability.
Area of Science:
- Materials Science
- Computational Chemistry
- Chemical Physics
Background:
- Thermal conductivity in energetic molecular crystals is crucial for safety.
- Temperature dependence of thermal conductivity is poorly understood at the mode-resolved level.
- ε-CL-20 is an energetic material with significant safety implications.
Purpose of the Study:
- To elucidate the mechanisms behind the temperature dependence of thermal conductivity in ε-CL-20.
- To link macroscopic heat conduction to microscopic chemical reaction initiation.
- To develop a general framework for energy-flux networks in molecular solids.
Main Methods:
- Machine-learned potential (neuroevolution potential) with DFT accuracy.
- Vibrational dynamics analysis, including spectral energy density and phonon lifetimes.
- Mode-projection analysis and nonequilibrium mode-excitation simulations.
Main Results:
- Anisotropic thermal conductivity decreases significantly between 200-400 K.
- Phonon lifetimes shorten, and propagation shifts from particle-like to wave-like tunneling.
- Temperature strengthens anharmonic couplings, funneling energy towards reactive nitro-group vibrations.
Conclusions:
- Heat conduction degradation and reaction initiation are linked via anharmonic coupling.
- The cage-deformation mode acts as an energy-flux hub, directing heat towards reactive sites.
- This study provides a phonon-resolved link between heat transport and chemical reactivity in energetic materials.
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