title: Fast and Accurate Electronic Excitations in Cyanines with the Many-Body Bethe-Salpeter Approach.
abstract: The accurate prediction of the optical signatures of cyanine derivatives remains an important challenge in theoretical chemistry. Indeed, up to now, only the most expensive quantum chemical methods (CAS-PT2, CC, DMC, etc.) yield consistent and accurate data, impeding the applications on real-life molecules. Here, we investigate the lowest lying singlet excitation energies of increasingly long cyanine dyes within the GW and Bethe-Salpeter Green's function many-body perturbation theory. Our results are in remarkable agreement with available coupled-cluster (exCC3) data, bringing these two single-reference perturbation techniques within a 0.05 eV maximum discrepancy. By comparison, available TD-DFT calculations with various semilocal, global, or range-separated hybrid functionals, overshoot the transition energies by a typical error of 0.3-0.6 eV. The obtained accuracy is achieved with a parameter-free formalism that offers similar accuracy for metallic or insulating, finite size or extended systems.
authors.affiliation: CNRS, Institut NEEL , F-38042 Grenoble, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Boulanger
authors.affiliation: Laboratoire CEISAM-UMR CNRS 6230, Université de Nantes , 2 Rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3, France.|Institut Universitaire de France , 103, bd Saint-Michel, F-75005 Paris Cedex 05, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Jacquemin
authors.affiliation: INAC, SP2M/L_Sim, CEA/UJF Cedex 09, 38054 Grenoble, France.
authors.forename: Ivan
authors.initials: I
authors.lastname: Duchemin
authors.affiliation: CNRS, Institut NEEL , F-38042 Grenoble, France.|University Grenoble Alpes, Institut NEEL , F-38042 Grenoble, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Blase