A5103044056- Energetic Materials and Combustion
- Crystallography and molecular interactions
- High-Velocity Impact and Material Behavior
- Thermal and Kinetic Analysis
- Combustion and Detonation Processes
- High-pressure geophysics and materials
- Muon and positron interactions and applications
- Nonlinear Optical Materials Research
- Chemical Thermodynamics and Molecular Structure
- Structural Response to Dynamic Loads
- Luminescence and Fluorescent Materials
- Organic and Molecular Conductors Research
- Spectroscopy and Quantum Chemical Studies
- Laser-Plasma Interactions and Diagnostics
- Quantum, superfluid, helium dynamics
- Fluid Dynamics Simulations and Interactions
Institute of Applied Physics and Computational Mathematics
2014-2022
California Institute of Technology
2012-2019
Weatherford College
2018
Beijing Institute of Technology
2010-2017
Effects of molecular vacancies on the decomposition mechanisms and reaction dynamics condensed-phase β-HMX at various temperatures were studied using ReaxFF simulations. Results show that three primary initial mechanisms, namely, N−NO2 bond dissociation, HONO elimination, concerted ring fission, exist both high lower temperatures. The contribution to HMX is influenced by vacancies, effects vary with temperature. At temperature (2500 K), remarkably promote N−N cleavage breaking but hinder...
We report reactive molecular dynamics simulations using the ReaxFF force field to examine shock-induced hot-spot formation followed by detonation initiation in realistic (2.7 million atoms) models of polymer bonded explosives (PBX) with nonplanar interfaces. considered here two energetic materials (EMs) pentaerythritol tetranitrate (PETN), a common EM for PBX, and silicon (Si-PETN), which is so extremely sensitive that it has not been possible characterize its shock properties...
We report here the predictions on anisotropy of shock sensitivity and chemical process initiation in single crystal β-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (β-HMX) using compressive shear reactive dynamics (CS-RD) model with ReaxFF-lg force field. Analysis resolved stress induced by uniaxial compression along three directions normal to (110), (011), (010) planes leads identify eight slip systems as candidates for deformation. For each systems, non-equilibrium simulations were...
We report million-atom reactive molecular dynamic simulations of shock initiation β-cyclotetramethylene tetranitramine (β-HMX) single crystals containing nanometer-scale spherical voids. Shock induced void collapse and subsequent hot spot formation as well chemical reaction are observed which depend on the size impact strength. For an velocity 1 km s(-1) a radius 4 nm, process includes three stages; dominant mechanism is convergence upstream molecules toward centerline downstream surface...
To gain an atomistic-level understanding of the thermal and chemical responses condensed energetic materials under shock, we developed a shock reactive dynamics (TS-RD) computational protocol using molecular simulation coupled with ReaxFF force field. β-Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) was selected as target explosive due to its wide usage in military industry. The results show that initiated by large temperature gradient between “hot” region “cold” expansion particles...
Molecular dynamics simulations require accurate force fields (FFs) to describe the physical and chemical properties of complex materials systems. FF parameters for valence interactions can be determined from high-quality Quantum Mechanical (QM) calculations. However, it has been challenging extract long-range nonbonded interaction potentials QM calculations since there is no unambiguous method separate total energy into electrostatics (polarization), van der Waals (vdW), other components....
The development of new energetic materials (EMs) with improved detonation performance but low sensitivity and environmental impact is considerable importance for applications in civilian military fields. Often designs are difficult to synthesize so predictions advance most valuable. Examples include MTO (2,4,6-triamino-1,3,5-triazine-1,3,5-trioxide) MTO3N (2,4,6-trinitro-1,3,5-triazine-1,3,5-trioxide) suggested by Klapötke as candidate EMs not yet successfully synthesized. We propose apply...
Recently quantum mechanical (QM) calculations on a single Si-PETN (silicon-pentaerythritol tetranitrate) molecule were used to explain its colossal sensitivity observed experimentally in terms of unique Liu carbon-silyl nitro-ester rearrangement (R3Si-CH2-O-R2→ R3Si-O-CH2-R2). In this paper we expanded the study from bulk system by extending ReaxFF reactive force field describe similar Si-C-H-O-N systems with parameters optimized reproduce QM results. The reaction mechanisms and kinetics...
The response to temperature of HMX polymorph is important for understanding the sensitivity, stability, and phase transitions energetic material. Using ReaxFF-lg with isothermal-isobaric molecular dynamics (NPT-MD) methods, crystal structures -, -HMX crystals in a range 303-503 K at atmospheric pressure are investigated. calculated thermal expansion coefficients general agreements experimental results, indicating that potential can correctly describe polymorph. linear indicate anisotropic,...
Anisotropic sensitivity is related to different intermolecular steric arrangements across the slip plane induced by shock compression along various orientations.
A general strategy is presented to develop an all-atom, non-empirical, and tailor-made force field (NETMFF) for high explosives (HEs). The central part of the a self-consistent (SCFF) optimization technique. consistence ensured by iterating parameterization procedure. generation reliable ab initio reference data optimizing NETMFF parameters SCFF technique are discussed in detail. Starting with crystal structure obtained from either experiment or prediction (CSP), can be developed only first...
The intramolecular differences of four compounds lead to significant distinctions in the reaction mechanisms and sensitivity under heating.
Abstract:
Anisotropic sensitivity is related to the different intermolecular steric arrangements across slip plane induced by shock compression along various orientations.