Theoretical analysis of the terahertz spectrum of the high explosive PETN

Damian G. Allis, Timothy M. Korter

Research output: Contribution to journalArticle

101 Scopus citations

Abstract

The experimental solid-state terahertz (THz) spectrum (3 to 120 cm -1) of the high explosive pentaerythritol tetranitrate (PETN, C 5H6N4O12) has been modeled using solid-state density functional theory (DFT) calculations. Solid-state DFT, employing the BP density functional, is in best qualitative agreement with the features in the previously reported THz spectrum. The crystal environment of PETN includes numerous intermolecular hydrogen-bonding interactions that contribute to large (up to 80 cm-1) calculated shifts in molecular normal-mode positions in the solid state. Comparison of the isolated-molecule and solid-state normal-mode calculations for a series of density functionals reveals the extent to which the inclusion of crystal-packing interactions and the relative motions between molecules are required for correctly reproducing the vibrational structure of solid-state THz spectra. The THz structure below 120 cm-1 is a combination of both intermolecular (relative rotations and translations) and intramolecular (torsions, large amplitude motions) vibrational motions. Vibrational-mode analyses indicate that the first major feature (67.2 cm-1) in the PETN THz spectrum contains all of the optical rotational and translational cell modes and no internal (molecular) vibrational modes.

Original languageEnglish (US)
Pages (from-to)2398-2408
Number of pages11
JournalChemPhysChem
Volume7
Issue number11
DOIs
StatePublished - Nov 13 2006

Keywords

  • Computer chemistry
  • Density functional calculations
  • Hydrogen bonds
  • Solid-state structures
  • Vibrational spectroscopy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

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