Vibrational properties of organic donor-acceptor molecular crystals: Anthracene-pyromellitic-dianhydride (PMDA) as a case study

摘要: We establish a reliable quantum-mechanical approach to evaluate the vibrational properties of donor-acceptor molecular crystals. The anthracene-PMDA (PMDA = pyromellitic dianhydride) crystal, where anthracene acts as electron donor and PMDA acceptor, is taken representative system for which experimental non-resonance Raman spectra are also reported. first investigate impact that amount nonlocal Hartree-Fock exchange (HFE) included in hybrid density functional has on geometry, normal modes, electronic coupling, electron-vibrational (phonon) couplings. comparison between theoretical indicates results based αPBE with 25%-35% HFE better agreement compared those obtained pure PBE functional. Then, taking 25% HFE, we assign modes examine their contributions relaxation energy related electron-vibration interactions. show largest contribution (about 90%) due interactions low-frequency modes. found be about five times smaller than coupling.