Assessment of Functionals for TD-DFT Calculations of Singlet−Triplet Transitions

Abstract

The calculation of transition energies for electronically excited states remains a challenge in quantum chemistry, for which time-dependent density functional theory (TD-DFT) is often viewed as a balanced (computational effort/obtained accuracy) technique. In this study, we benchmark 34 DFT functionals in the specific framework of TD-DFT calculations for singlet-triplet transitions. The results are compared to accurate wave function data reported for the same set of 63 excited-states, and it turns out that, within the selected TD-DFT framework, BMK and M06-2X emerge as the most efficient hybrids. This investigation clearly illustrates that the conclusions drawn for singlet excited states do not necessarily hold for triplet states, even for similar molecular structures.

Benchmarking the performance of time-dependent density functional methods

“…With the exception of the CAM-B3LYP (MAE = 1.10 eV) functional, the errors associated with triplet excited states are near or below the errors for singlet excited states. These results for the triplet excited states are different from the work of Jacquemin et al, 41 which suggests MAE values larger than 0.40 eV for PBE0 and B3LYP. The difference between the current benchmark study and that of Jacquemin et al is that in the current study the performance of the functionals is compared with experimentally determined excitation energies, whereas the previous analysis by Jacquemin et al compared functional performance with predictions from wave function methods.…”

“…Several benchmark studies [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] have explored the performance of using ground-state density functionals within the adiabatic approximation for the calculation of vertically excited states using TDDFT. The scope of the previous benchmark studies has been primarily limited to singlet valence excited states [36][37][38][39] with very few benchmarks considering triplet valence [40][41][42] or singlet and triplet Rydberg excited states.…”

“…The scope of the previous benchmark studies has been primarily limited to singlet valence excited states [36][37][38][39] with very few benchmarks considering triplet valence [40][41][42] or singlet and triplet Rydberg excited states. 40,43 Furthermore, the approach taken with previous benchmark studies 36,37,[40][41][42] was to perform ground state geometry optimizations using a single level of theory (PBE0 functional or Møller Plesset second-order perturbation theory 51 ) followed by vertical excited state calculations with varying density functionals. Alternatively, the same density functional can be used for both the ground-state geometry optimization and vertical excited state energy calculation.…”

Electrochemistry and time dependent DFT study of a (vinylenedithio)-TTF derivative in different oxidation states

“…[61]/6-31+G(d) and BMK/def2-TZVPP+R [62,63] level of theory employing the CPCM [64,65] solvent model and dichloromethane as the solvent [66]. Full convergence of the SCF procedure was requested with the SCF = tight keyword.…”

Application of recent double-hybrid density functionals to low-lying singlet-singlet excitation energies of large organic compounds

“…This effect is inherent to the choice of the functional, which actually determines the final quality of the TD-DFT excited-states properties. Over the past years, numerous successful (mainly with organic compounds) benchmarking studies [8][9][10][11][12][13][14][15][16][17][18][19] were carried out providing relevant guidelines to reach accuracy for many molecular systems and various physico-chemical properties.…”