Calculation of anharmonic couplings and THz linewidths in crystalline PETN

A Pereverzev and TD Sewell and DL Thompson, JOURNAL OF CHEMICAL PHYSICS, 140 (2014).

DOI: 10.1063/1.4866896

We have developed a method for calculating the cubic anharmonic couplings in molecular crystals for normal modes with the zero wave vector in the framework of classical mechanics, and have applied it, combined with perturbation theory, to obtain the linewidths of all infrared absorption lines of crystalline pentaerythritol tetranitrate in the terahertz region (<100cm-1). Contributions of the upand down- conversion processes to the total linewidth were calculated. The computed linewidths are in qualitative agreement with experimental data and the results of molecular dynamics simulations. Quantum corrections to the linewidths in the terahertz region are shown to be negligible. (c) 2014 AIP Publishing LLC.

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