Terahertz spectroscopy of the crystalline α-quaterthiophene: A combined experimental and density functional theory study

We investigated the terahertz phonon modes in the α-quaterthiophene using infrared and inelastic neutron scattering spectroscopy in the 0.3-1.5 THz, and DFT calculations. The experimental infrared spectrum is dominated by two phonon modes assigned to an antiphasis translation and a libration of rings.