Electronic Structure Modifications Induced by Nanosize Lattice Imperfections in Molecular Crystals


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A first-principles theoretical modeling of basic defects such as a molecular vacancy, a vacancy dimer, an edge dislocation, and a nano-crack in organic molecular crystals, particularly solid RDX (C3H6N6O6) and PETN (C5H8N4O12), is presented. It is established that shock compression changes the optical properties of both the defect-free crystal and the crystal with defects by narrowing the optical band gap. The lattice defects (especially dislocations) are identified with the so-called “hot spots” in triggering the explosive detonation. We found that the edge dislocations produce local electronic states in the gap whereas the external pressure moves these states deep within the band gap. This creates favorable conditions for the critical chemical bond rupture due to exciton formation. Relation between defects, hot spot formations, the sensitivity of solids to initiation, and particular applications of the obtained results are briefly discussed.

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Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2001 International Conference on Computational Nanoscience and Nanotechnology
Published: March 19, 2001
Pages: 65 - 68
Industry sector: Advanced Materials & Manufacturing
Topic: Informatics, Modeling & Simulation
ISBN: 0-9708275-3-9