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Observation of deflagration wave in energetic materials using reactive molecular dynamics

Evidence and attribution

Authority of statements

Prose sections below (Summary, Methods, Findings, etc.) are curated summaries of the publication identified by doi, title, and pdf_path in the front matter above. They are not new primary claims by this wiki.

For definitive numerical values, reaction pathways, and flux analyses, use the peer-reviewed article (and optional records under normalized/papers/ when present)—not this page alone.

Summary

Continuum models of condensed-phase energetic materials often rely on simplified chemistry at combustion fronts, while atomistic detail of a moving deflagration wave remains difficult to treat uniformly across systems. This work uses ReaxFF-based reactive molecular dynamics in LAMMPS to study thermally initiated deflagration in crystalline RDX, mapping trajectories onto Eulerian control volumes to obtain mass, energy, and chemical fluxes across the front. The authors describe a transition from ignition to a self-sustaining deflagration when mass transport at the front overtakes thermal transport during propagation, accompanied by a sharp temperature rise and increased density of unreacted solid ahead of the front. Reported energy flux across the propagating front is said to agree with prior heat-of-explosion estimates. Chemical analysis in the paper emphasizes inter- and intramolecular hydrogen transfer, formation of short-lived heavier polyradicals (analogous to nonvolatile residue discussed elsewhere), and a front composition described as molten RDX with radicals and intact triazine motifs.

Methods

A — Force-field training / fitting: ReaxFF for RDX chemistry using the Wood et al. parametrization cited in the article—no new fitting in this Combustion and Flame contribution.

B — Molecular dynamics / sampling: LAMMPS ReaxFF on γ-RDX supercell (PBC). Hot spot (~144 molecules) gets short high-T pulse under NVT while bulk remains NVE; then full-cell NVE (0.1 fs) to mimic adiabatic response. Post-process: Eulerian control volumes for mass, energy, species fluxes across deflagration front.

C — DFT / static QM: Not the engine for deflagration trajectories summarized here.

D — Review / non-simulation framing: Application paper mapping atomistic fronts to continuum-style flux language—not a methods review.

Engine: LAMMPS ReaxFF on γ-RDX supercell with PBC. System: crystalline RDX supercell with a hot-spot subset (~144 molecules) receiving a short high-T pulse under NVT while the remainder is NVE, followed by full-cell NVE propagation (Combustion and Flame Methods). Timestep: 0.1 fs for the NVE propagation quoted on this page. Thermostat: NVT segment on the hot spot only (thermostat family/damping in PDF). Duration / staging: total simulation time after initiation and equilibration splits are not transcribed here—use pdf_path. Barostat / pressure: N/A — NVE/NVT deflagration protocol without NPT control in the summary. Electric field: N/A — not used. Replica / enhanced sampling: N/A — not used.

Findings

The mapped fluxes support a picture in which a self-sustaining deflagration arises once mass transport at the front exceeds thermal transport, with the temperature spike and densification of cold material ahead of the front called out as signatures. Energy flux through the front is consistent with earlier heat-of-explosion-scale expectations in their analysis. The chemistry at the front is dominated by H-transfer chemistry and polyradical buildup, with triazine rings persisting within the described reactive mixture.

Comparisons. Energy flux at the front is compared to literature heat-of-explosion-scale estimates as cited in the article.

Corpus / PDF honesty. Flux thresholds and full species tables should be taken from pdf_path / extract pointers, not from this summary alone.

Limitations

  • A single initiation protocol and finite supercell restrict generality to other microstructures, defects, or initiation modes.
  • ReaxFF chemistry is approximate under the extreme temperatures and densities of a deflagration front; interpretation relies on the chosen parameter set.
  • Connection to continuum propellant models remains via conceptual comparison rather than direct coupling.

Relevance to group

Illustrates ReaxFF + LAMMPS applied to condensed-phase energetic materials and reaction-front diagnostics—useful alongside other reactive-MD combustion and decomposition work in the knowledge base.

Citations and evidence anchors

Reader notes (navigation)

  • reaxff-family
  • RDX and condensed-phase deflagration (reactive MD literature cross-links via theme hub above)