Electronic structure of molecular crystals containing edge dislocations

摘要

An attempt to model the electronic structure of molecular crystals containing an edge dislocation at the ab initio Hartree-Fock level is performed. The experimentally determined configurations for edge-type dislocations with the Burgers vector 001 in crystalline cyclotrimethylene trinitramine (RDX) and pentaetythritol tetranitrate (PETN) are theoretically simulated. It is shown that a shear stress, induced by the dislocations, produces local electronic states in the fundamental band gap of the crystal. These states are mainly formed by molecular orbitals of critical bonds (which are the N-NO2 group in RDX and the O-NO2 group in PETN) responsible for the stability of the materials. Optical absorption attributed to these electronic states is predicted and compared to the available experimental data. Properties of the defective solids are compared with those of the perfect crystals. Correlation of the electronic structure and sensitivity of the materials to initiation of a chemical reaction as well as some practical applications of the obtained results are discussed. (C) 2001 American Institute of Physics. References: 59