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Combustion of 1,5-dinitrobiuret (DNB) in the presence of nitric acid using ReaxFF molecular dynamics simulations (galley PDF)

Evidence and attribution

Authority of statements

This slug is a galley PDF for the JPCA article also covered by 2013russo-venue-jp403511q.

Summary

Reactive MD with a ReaxFF parametrization fit to quantum data for model species explores mixtures of 1,5-dinitrobiuret (DNB) and nitric acid at 0.5 and 1.0 g/mL, targeting dense vapor- and liquid-like conditions. Simulations identify composition regimes where kinetics produce a sharp thermal-energy release interpreted as spontaneous ignition / hypergolic-like behavior, with discussion of dominant mechanistic steps.

Methods

Grounding (galley): papers/Russo_DNB_HNO3_JPCA_2013_galley.pdf; normalized/extracts/2013russo-venue-research_p1-2.txt aligns with the same Computational Methods narrative as 2013russo-venue-jp403511q. Prefer paper:2013russo-venue-jp403511q for non-galley pagination when available.

1 — MD application (mixtures + ramps)

  • Engine / code: Reactive MD with ReaxFF; parameter distribution supports standalone ReaxFF, LAMMPS, and ADF ReaxFF (Computational Methods excerpt; same text as 2013russo-venue-jp403511q).
  • System / PBC (mixtures, excerpt-backed): 18 DNB + 18 HNO\(_3\) and 37 + 37 in 2.5 nm periodic cubes for ~0.5 and ~1.0 g/mL, plus an 18 DNB / 180 HNO\(_3\) case with enlarged box side lengths 3.65 nm and 2.91 nm as printed in the excerpt (2013russo-venue-jp403511q galley/VOR Methods opening).
  • Mixture equilibration/production protocol: After minimization, each mixture system is run for 5 ps NVT equilibration at 500 K using a Berendsen thermostat (500 fs damping), followed by NVE production at 500 K with \(\Delta t = 0.1\) fs, typically 500 ps total (some runs extended/shortened depending on reactivity). These lines are readable from the same article text in papers/Russo_DNB_HNO3_JPCA_2013.pdf (Simulation Details); the galley pdf_path on this slug is harder to extract reliably, so prefer the non-galley PDF bytes when auditing.
  • Single-molecule ramps (excerpt-backed): 20 runs with one DNB in a 2.5 nm periodic box, Berendsen heating to 4000 K, 500 fs damping, 0.1 fs timestep; terminal NO\(_2\) loss is the dominant first step in all 20 simulations (Computational Methods excerpt).
  • Barostat: N/A — not stated for these excerpts.
  • Temperature: 4000 K ramp target for single-molecule tests; mixture run temperatures are not stated on the indexed excerpt pages.
  • Pressure: N/A.
  • Electric field: N/A.
  • Replica / enhanced sampling: N/A.

2 — Force-field training

Same Jaguar B3LYP / 6-311G++** QM reference energies for DNB dissociations and DCA→DNB steps, trained into the C/H/O/N hypergolic ReaxFF extension, with ~6–8 kcal/mol agreement claims for highlighted steps (2013russo-venue-jp403511q excerpt).

Findings

  • Outcomes & mechanisms: Sharp thermal-energy release at some mixture compositions/densities, interpreted as spontaneous ignition / hypergolic-like behavior (abstract), with mechanistic decomposition tied to DNB/HNO\(_3\) chemistry in the Results discussion.
  • Comparisons: QM energy matching for trained channels and positioning vs hypergolic ionic liquid motivation literature (Introduction excerpt).
  • Sensitivity / design levers: 0.5 vs 1.0 g/mL and stoichiometry variants (including highly asymmetric ratios and pure-component controls) are explicit composition knobs in the Methods narrative on this galley-oriented page.
  • Limitations & outlook: Reactive FF studies omit multiphase fluid transport and drop-test hydrodynamics; see Limitations section on this page for modeling scope caveats.
  • Corpus honesty: Galley PDF; confirm numbers against paper:2013russo-venue-jp403511q + non-galley PDF if discrepancies are suspected.

Limitations

Reactive FF fidelity is limited by training chemistry; real propellant interfaces involve multiphase flow and transport not fully captured in these atomistic cells.

Relevance to group

ReaxFF application to ionic-liquid / hypergolic-chemistry motifs linked to nitric-acid oxidizers, with PSU authorship.

Citations and evidence anchors

  • DOI: 10.1021/jp403511q
  • Extract: normalized/extracts/2013russo-venue-research_p1-2.txt