title: Molecular dynamics study of the pressure-dependent terahertz infrared absorption spectrum of α- and γ-RDX.
abstract: Terahertz infrared absorption spectra of the α and γ polymorphs of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) were predicted using two different theoretical approaches based on molecular dynamics simulations. The thermodynamic conditions studied were T = 298 K and hydrostatic pressures P = 0.0, 1.0, and 2.0 GPa for α-RDX and P = 3.0, 5.2, and 7.0 GPa for γ-RDX. The spectra obtained using the two methods are similar but not identical. In the case of α-RDX for pressure P = 0.0 GPa both spectra agree reasonably well with experimental data. The predicted spectra for α-RDX exhibit red-shifting (mode softening) of the main absorption peak with increasing pressure while for γ-RDX the spectra exhibit overall blue-shifting with increasing pressure.
authors.affiliation: Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600, USA. pereverzeva@missouri.edu
authors.forename: Andrey
authors.initials: A
authors.lastname: Pereverzev
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Sewell
authors.forename: Donald L
authors.initials: DL
authors.lastname: Thompson