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Development and validation of COMPASS force field parameters for molecules with aliphatic azide chains
Michael J McQuaid1, Huai Sun, David Rigby
1US Army Research Laboratory, AMSRL-WM-BD, Aberdeen Proving Ground, Maryland 21005, USA. mcquaid@arl.army.mil
Journal of Computational Chemistry
|November 25, 2003
Summary
New force field parameters accurately predict thermophysical properties for materials with aliphatic azide chains. Molecular dynamics simulations show good agreement with experimental data for density and heat of vaporization.
Area of Science:
- Materials Science
- Computational Chemistry
- Chemical Engineering
Background:
- Accurate prediction of condensed-phase thermophysical properties is crucial for materials design.
- Existing force fields lack parameters for aliphatic azide chains, limiting their predictive power.
- Aliphatic azides are relevant in energetic materials and as potential hydrazine alternatives.
Purpose of the Study:
- To develop and validate a force field capable of accurately predicting thermophysical properties for materials containing aliphatic azide chains.
- To establish molecular modeling capabilities for these unique chemical structures.
- To support the design and application of novel azide-containing materials.
Main Methods:
- Development of new atom types and potential parameters for aliphatic azide chains within the COMPASS force field.
- Gas-phase calculations of molecular structures and vibrational frequencies for model compounds.
- Molecular dynamics (MD) simulations to calculate liquid densities and heats of vaporization.
- Validation against experimental data and computational quantum mechanics results.
Main Results:
- Four new atom types were defined for azide nitrogen and bonded carbon atoms.
- Expanded force field accurately reproduced gas-phase structures and frequencies for hydrazoic acid and azidoalkanes.
- MD simulations showed good agreement with experimental liquid densities for most training compounds.
- Simulated heats of vaporization were in reasonable agreement with experimental values.
- Reasonable density predictions were achieved for novel 2-azidoethanamines.
Conclusions:
- The developed force field parameters enhance the predictive accuracy for thermophysical properties of aliphatic azide-containing materials.
- Molecular modeling is a viable tool for understanding and designing materials with azide functionalities.
- This work facilitates the exploration of aliphatic azides in applications such as alternative fuels.
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