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Monday, January 26, 2015
10:00 AM - 11:00 AM
CNLS Conference Room (TA-3, Bldg 1690)


Theoretical methods of obtaining IR spectra in molecular crystals

Andrey Pereverzev
Department of Chemistry, University of Missouri-Columbia

I will describe various methods for constructing theoretical IR absorption spectra and vibrational densities of states in molecular crystals and then discuss applications of those methods to predict IR line widths and spectra of the polyatomic molecular crystalline explosives PETN and RDX. Spectra were constructed using the mode-relaxation method [JCP 134, 014513 (2011)] and from the Fourier transform of the dipole time autocorrelation functions. The mode-relaxation method is based on normal-mode analysis of Hessian matrices. Line widths of IR-active modes were obtained using both the mode-relaxation method and perturbation theory calculations. We also developed an alternative way of obtaining the Hessian from the force covariance matrix in the canonical ensemble that could be used in the mode-relaxation and perturbation theory calculations. Theoretical and simulation results will be compared to data.

Host: Andrei Piryatinski (T-4)