We now examine whether our framework can be used to predict electronic coupling and diffusion coefficients for fused-ring electron acceptor (FREA) molecules. FREA crystals are known to exhibit high exciton diffusion coefficients and are also attracting attention as materials for nextgeneration organic solar cells. These molecules also possess large and complicated three-dimensional structures, making them a tough benchmark for our framework. Figure compares the exciton coupling parameters as predicted by our framework and Equation ( ) with reference ones obtained using DFT. Each point corresponds to one FREA dimer extracted from the FREA crystal. The predicted and reference values agree well with each other overall, while couplings for the EH-IDTBR dimers and a Y6 dimer predicted less well.