Charge Transfer in Molecular Cocrystals: A Plane Wave vs Localized-Orbital View─Structural Information Obtained from Calculated Raman and IR Phonons

This article aims at laying the foundation for the development of electronic structure-property relationships in the field of charge-transfer (CT) organic semiconductors by studying the low-frequency phonon response of donor-acceptor (DA) compounds. In this article, it is shown and discussed how and why phonon frequencies and their delocalization depend on the interplay between single-molecule properties and crystal structures. These results are obtained by combining results from state-of-the-art quantum-mechanical calculations, carried out within both localized orbitals and a plane wave paradigm, with simple classical models. CT compounds obtained from perylene (Pery) as the donor and FnTCNQ (n = 0, 4) as the acceptors are considered.