Molecular dynamics study of the effect of pressure on the terahertz-region infrared spectrum of crystalline pentaerythritol tetranitrate

► THz IR absorption spectra of PETN crystal were calculated using two MD methods. ► Spectra were calculated at T = 298 K for pressures P = 0, 1, 2, and 3 GPa. ► The two approaches yield similar predictions for the spectra. ► The terahertz spectra exhibit an overall blue shift with increasing pressure. ► Pressure-dependent Raman spectra at higher frequencies provide indirect validation.