title: Quantifying charge resonance and multiexciton character in coupled chromophores by charge and spin cumulant analysis.
abstract: We extend excited-state structural analysis to quantify the charge-resonance and multi-exciton character in wave functions of weakly interacting chromophores such as molecular dimers. The approach employs charge and spin cumulants which describe inter-fragment electronic correlations in molecular complexes. We introduce indexes corresponding to the weights of local, charge resonance, and biexciton (with different spin structure) configurations that can be computed for general wave functions thus allowing one to quantify the character of doubly excited states. The utility of the approach is illustrated by applications to several small dimers, e.g., He-H2, (H2)2, and (C2H4)2, using full and restricted configuration interaction schemes. In addition, we present calculations for several systems relevant to singlet fission, such as tetracene, 1,6-diphenyl-1,3,5-hexatriene, and 1,3-diphenylisobenzofuran dimers.
authors.affiliation: STC "Institute for Single Crystals," National Academy of Sciences, Kharkov 61001, Ukraine.
authors.forename: Anatoliy V
authors.initials: AV
authors.lastname: Luzanov
authors.affiliation: Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia International Physics Center (DIPC), P.K. 1072, 20080 Donostia, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Casanova
authors.affiliation: Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA.
authors.forename: Xintian
authors.initials: X
authors.lastname: Feng
authors.affiliation: Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA.
authors.forename: Anna I
authors.initials: AI
authors.lastname: Krylov