Extensive TD-DFT Benchmark: Singlet-Excited States of Organic Molecules

Abstract

Extensive Time-Dependent Density Functional Theory (TD-DFT) calculations have been carried out in order to obtain a statistically meaningful analysis of the merits of a large number of functionals. To reach this goal, a very extended set of molecules (∼500 compounds, >700 excited states) covering a broad range of (bio)organic molecules and dyes have been investigated. Likewise, 29 functionals including LDA, GGA, meta-GGA, global hybrids, and long-range-corrected hybrids have been considered. Comparisons with both theoretical references and experimental measurements have been carried out. On average, the functionals providing the best match with reference data are, one the one hand, global hybrids containing between 22% and 25% of exact exchange (X3LYP, B98, PBE0, and mPW1PW91) and, on the other hand, a long-range-corrected hybrid with a less-rapidly increasing HF ratio, namely LC-ωPBE(20). Pure functionals tend to be less consistent, whereas functionals incorporating a larger fraction of exact exchange tend to underestimate significantly the transition energies. For most treated cases, the M05 and CAM-B3LYP schemes deliver fairly small deviations but do not outperform standard hybrids such as X3LYP or PBE0, at least within the vertical approximation. With the optimal functionals, one obtains mean absolute deviations smaller than 0.25 eV, though the errors significantly depend on the subset of molecules or states considered. As an illustration, PBE0 and LC-ωPBE(20) provide a mean absolute error of only 0.14 eV for the 228 states related to neutral organic dyes but are completely off target for cyanine-like derivatives. On the basis of comparisons with theoretical estimates, it also turned out that CC2 and TD-DFT errors are of the same order of magnitude, once the above-mentioned hybrids are selected.

Acene‐Modified Triphenylamine Dyes for Dye‐Sensitized Solar Cells: A Computational Study

“…The improvements in CPU resources now allow the study, at correlated levels of approximation, of the absorption spectra of large molecular species such as the dyes used in DSSCs. The state-of-the-art computational methodologies based on DFT and TDDFT provide accurate results and reproduce well the optical properties of various Ru II complexes [26][27][28] and metal-free organic dyes, [29][30][31][32][33][34] along with their ground-and excited-state oxidation potentials. The "cyanine-like" molecules, such as TPA dyes, show electronic excitations with large charge-transfer character, which make them difficult to study by DFT calculations.…”

Nonempirical Double-Hybrid Functionals: An Effective Tool for Chemists

“…Despite of the fully theoretical approach used to hybridize it, this functional is comparable in accuracy to B3LYP, when not better for specific properties. [37][38][39][40] . Figure 1 shows the impact of the exact-exchange fraction on the accuracy for the atomization energy of the G2-148 dataset.…”

Benchmarking the performance of time-dependent density functional 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.…”