Modeling Solid-Solid Phase Transitions in PETN Using Density Functional Theory
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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We present density functional theory DFT calculations of a stable orthorhombic phase of hydrostatically compressed pen-taerythritol tetranitrate PETN. In these calculations, an orthorhombic a not equal b not equal c structure optimized at a very high pressure was used to initialize crystal structure optimizations at progressively lower pressures until the optimization spontaneously reverted to a tetragonal phase a b not equal c. The orthorhombic crystal structures exhibit P21212 symmetry and a lowering of molecular symmetry from S4 to C2, which matches the orthorhombic PETN III phase debated in the literature. These findings are consistent across several DFT methods however, the predicted transition pressures range from 16 to 23 GPa depending on the type of the functional and the size of the periodic supercell.
- Quantum Theory and Relativity
- Physical Chemistry