title: Modeling the Emission Spectra of Organic Molecules: A Competition between Franck-Condon and Nuclear Ensemble Methods.
abstract: The emission spectra of flexible and rigid organic molecules are theoretically investigated in the framework of the Franck-Condon (FC) and nuclear ensemble (NE) approaches, both of which rely on results from density functional theory but differ in the way vibrational contributions are taken into account. Our findings show that the emission spectra obtained using the NE approach are in better agreement with experiment than the ones produced by FC calculations considering both rigid and flexible molecules. Surprisingly, the description of a suitable balance between the vibronic progression and the emission spectra envelope shows dependency on the initial sampling for the NE calculations which must be judiciously selected. Our results intend to provide guidance for a better theoretical description of light emission properties of organic molecules with applications in organic electronic devices.
authors.affiliation: Institute of Physics, University of Brasília , 70.919-970 Brasília, Brazil.
authors.forename: Leonardo Evaristo
authors.initials: LE
authors.lastname: de Sousa
authors.affiliation: Institute of Physics, University of Brasília , 70.919-970 Brasília, Brazil.
authors.forename: Luiz Antonio
authors.initials: LA
authors.lastname: Ribeiro
authors.affiliation: Institute of Physics, University of Brasília , 70.919-970 Brasília, Brazil.
authors.forename: Antonio Luciano de Almeida
authors.initials: AL
authors.lastname: Fonseca
authors.affiliation: Institute of Physics, University of Brasília , 70.919-970 Brasília, Brazil.
authors.forename: Demétrio Antonio
authors.initials: DA
authors.lastname: da Silva Filho