Investigating Orientational Defects in Energetic Material RDX Using First-Principles Calculations.
Anirban Pal1, Vincent Meunier1, Catalin R Picu1
1Department of Mechanical, Aerospace and Nuclear Engineering and ‡Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
This study confirms the stability of four orientational defects in alpha-RDX using first-principles calculations. These defects, linked to material sensitivity, may be identifiable via Raman spectroscopy.
Area of Science:
- Computational materials science
- Solid-state chemistry
- Molecular dynamics
Background:
- Orientational defects are molecular-scale point defects involving misaligned molecules.
- Previous empirical force field studies predicted their prevalence in alpha-RDX.
- These defects are hypothesized to influence material sensitivity.
Purpose of the Study:
- To confirm the stability of orientational defects in alpha-RDX using first-principles calculations.
- To evaluate their formation energies and annealing barrier heights.
- To investigate their impact on charge density and vibrational spectra.
Main Methods:
- First-principles calculations
- Density functional theory (DFT)
- Analysis of charge density distribution
- Vibrational spectrum evaluation
Main Results:
- The stability of four distinct orientational defects in alpha-RDX was confirmed.
- Formation energies and annealing barriers for these defects were calculated.
- Charge reduction was observed at the N-N bond midpoint in defective molecules.
- Band splitting in vibrational spectra indicates potential for experimental identification.
Conclusions:
- First-principles calculations validate the existence and stability of orientational defects in alpha-RDX.
- These defects exhibit charge redistribution linked to material initiation sensitivity.
- Observed spectral changes offer a pathway for experimental detection using Raman spectroscopy.
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