Modeling charge and energy transports in $\pi $-conjugated systems

A generic 3D model Hamiltonian is developed to simulate the charge and energy transports in $\pi $-conjugated composite materials. The intrachain interactions are described by our recently developed adapted Su-Schrieffer-Heeger Hamiltonian and the interchain $\pi \pi $ interactions are modeled using distance-dependent hopping integrals. Excellent agreements in their binding energetics and geometries with post-Hartree-Fock ab initio methods and experiments are found in the cases of a benzene dimer, graphene bi-layer, and poly-($p$-phenylene vinylene) (PPV) crystal. The computed photoinduced charge separated states and associated adsorption spectra of the PPV-C$_{60}$ and PPV-C$_{60}$-graphene agree perfectly with experimental measurements.