PyFREC: Software for Förster electronic coupling evaluation in molecular fragments

Electronic couplings are crucial for understanding exciton dynamics and associated energy transfer in artificial and natural chromophores. The proposed PyFREC (Python FRagment Electronic Coupling) software enables evaluation of electronic couplings based on the Förster model. PyFREC features the decomposition of electronic couplings, obtained through quantum chemical calculations, into the orientation and dipole strength components. Furthermore, the variation method to evaluate energies of coupled electronic excited states and delocalization of electronic excitations is implemented in the software. PyFREC has been tested on the S22 benchmark dataset of non-covalent complexes and water clusters. © 2016 Wiley Periodicals, Inc.