Can time-dependent double hybrid density functionals accurately predict electronic excitation energies of BODIPY compounds?

Abstract

The vertical excitation energies of 12 BODIPY chromophores are benchmarked via TD-DFT, using 36 functionals covering different rungs. It was found that most TD-DFT results overestimate the excitation energies, and provide mean absolute error (MAE) values larger than 0.4 eV. The dispersion-corrected, spin-component-scaled, double-hybrid (DSD) density functionals DSD-BLYP and DSD-PBEP86 are found to have the smallest MAE values of 0.119 eV and 0.124 eV, respectively. The low MAE values of the two DSD density functionals falls in the range of errors found in the wavefunction based methods that are reported to be suitable methods for such chromophores. DSD-BLYP and DSD-PBEP86 functionals also show excellent consistency (standard deviation = 0.076 eV and 0.082 eV respectively) and good predictability (linear determination coefficient R2 = 0.933 eV and 0.917 eV respectively). MAE values of the two spin-component-scaled DH functionals of vertical fluorescence calculations are also promising (MAE around 0.12 eV).