For the search for promising singlet fission candidates, the calculation of the effective electronic coupling, which is required to estimate the singlet fission rate between the initially excited state (S0S1) and the multiexcitonic state ((TT)-T-1, two triplets on neighboring molecules, coupled into a singlet), should be sufficiently reliable and fast enough to explore the configuration space. We propose here to modify the calculation of the effective electronic coupling using a nonorthogonal configuration interaction approach by: (a) using only one set of orbitals, optimized for the triplet state of the molecules, to describe all molecular electronic states, and (b) only taking the leading configurations into consideration. Furthermore, we also studied the basis set convergence of the electronic coupling, and we found, by comparison to the complete basis set limit obtained using the cc-pVnZ series of basis sets, that both the aug-cc-pVDZ and 6-311++G** basis sets are a good compromise between accuracy and computational feasibility. The proposed approach enables future work on larger clusters of molecules than dimers.

Journal of computational chemistry

EXCITON MODEL; WAVE-FUNCTIONS; effective electronic coupling; AB-INITIO; nonorthogonal configuration interaction; CHEMISTRY; DYNAMICS; basis set limit; TETRACENE; SYSTEMATIC SEQUENCES; VB-SCF; singlet fission; Coupling (molecular); Couplings; Electron states; Mathematical analysis; Dimers; Configuration interaction; Fission; Atomic energy levels; Index Medicus; Full Paper; Full Papers; nonorthogonal configuration interaction; basis set limit; effective electronic coupling; singlet fission

PubMed; ProQuest Computer Science Collection; MEDLINE - Academic