Molecular Scale Theoretical Studies of Energy Deposition and Redistribution in Crystalline High Explosives to Stimulate Enhanced Detectable Signatures
Abstract
In this project we have developed two molecular dynamics-based methods for simulating the THz-region infrared (IR) spectrum of molecular crystals. Both methods were designed for use at finite temperature and stress. The first method, referred to as the mode-relaxation approach, requires (1) the normal mode {i.e., phonon) eigenvectors and frequencies of the crystal, (2) the associated squared transition dipoles mu2 for all THz-region phonons with zero wave vector (k = 0), and (3) the spectral line width gamma for each k = 0 THz-region phonon with nonzero mu2 {i.e., the IR-active THzregion modes). These quantities are the ones required to specify the Lorentzian absorption profile for an individual spectral line. The eigenvectors, frequencies, and transition dipoles were obtained directly from normal mode analysis of the crystal, performed for crystal lattice parameters corresponding to a specified temperature and stress state. Line widths were determined separately for each THz mode by selectively depositing, in an otherwise thermalized crystal, a fixed amount of energy in a given normal mode and monitoring the time dependence of energy transfer from that mode.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 07, 2012
- Accession Number
- ADA562439
Entities
People
- Thomas D. Sewell