1. Simulations of Nanoparticles of Energetic Materials
Thompson
Simulations of Nanoparticles of Energetic Materials
Goal: Develop theoretical/computational methods and models to
describe physical and chemical properties of energetic
nanoparticles
Processes of Interest
 structure
 melting
chemical Decomposition
Thompson 1/2 with Saman Alavi
Molecular dynamics simulation is the primary computational method used in these studies.
The minimum energy structure of the nanoparticles is studied at each temperature starting from a ordered supercell
Melting in nanoparticles is not a sharp transition, as in bulk phases. This is due to surface effects. The onset and completion of melting need to be carefully determined.
By decomposition, chemical decomposition or physical evaporation of the nanoparticle is meant.
Systems of Interest
Al and Al2O3
nitromethane
HNIW

2. Thompson (cont.) New methods for characterizing nanoparticles
Progress and Accomplishments
Method Development
New methods for characterizing nanoparticles
Methods for determining the melting transition
Simulations
Oxidation of Al with pulsed oxygen supply
Diffusion of adsorbates on nanoparticles
Structures of nanoparticles as functions of temperature:
CH3NO2 and HNIW
Melting of nanoparticles as function of size:
Al, Al2O3, CH3NO2, and HNIW
“Decomposition” of nanoparticles:
sublimation and evaporation
Thompson 2/2 with Saman Alavi
The ratio of O to Al is less than 3:2 in the Al oxidation studies.
The melting point of a nanoparticle depends on its size. For large nanoparticles, the melting point seems to smoothly approach the bulk limit as the size of the nanoparticle increases.
The nitromethane studies appear in: S. Alavi and D. L. Thompson, J. Chem. Phys. 120, (2004).
Simulations at energies where reaction might occur result only in sublimation or evaporation