Evaluating the impact of Hartree-Fock exact exchange on the performance of global hybrid functionals for the vertical excited-state energies of fused-ring electron acceptors using TD-DFT

Amjad Ali; Tanveer Farid; Muhammad Imran Rafiq; Baojing Zhou; Weihua Tang

doi:10.1039/d2cp02228a

Evaluating the impact of Hartree-Fock exact exchange on the performance of global hybrid functionals for the vertical excited-state energies of fused-ring electron acceptors using TD-DFT

Phys Chem Chem Phys. 2022 Sep 14;24(35):21270-21282. doi: 10.1039/d2cp02228a.

Authors

Amjad Ali^{1

2}, Tanveer Farid^{1

2}, Muhammad Imran Rafiq², Baojing Zhou², Weihua Tang^{1

2}

Affiliations

¹ Institute of Flexible electronics (IFE, Future Technologies), Xiamen University, Xiamen 361005, P. R. China. whtang@xmu.edu.cn.
² School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.

PMID: 36043262
DOI: 10.1039/d2cp02228a

Abstract

The acceptor-donor-acceptor structured fused-ring electron acceptors (FREAs) have piqued interest for organic solar cells. We herein employ time-dependent density functional theory to evaluate the effect of Hartree-Fock exact exchange (HFX) on the performance of 16 global hybrid functionals for computing the maximum absorption wavelengths (λ_ver-theo) and the vertical excitation energies (E_ver-theo) of 34 molecules. We customize the HFX ratio in the functionals used to perform an in-depth analysis of its impact on the E_ver-theo values. The computed λ_ver-theo values strictly follow an inverse proportionality to the HFX percentage. The performance of the methods with the same ratio of HFX is almost identical, such as B3LYP, B3PW91, and mPW3PBE containing 20% HFX. The performance enhances with a relatively higher HFX ratio of 21% in X3LYP, B971, B972, and 22% in B98 giving smaller deviations. APF and APFD containing 23% HFX provide the smallest deviations for all compounds, with a mean signed error limited to 0.02 eV and a mean absolute error (MAE) of 0.06 eV. The performance drops using M06 and M05 with comparatively higher HFX ratios providing MAE values of 0.07 eV and 0.1 eV, respectively. M06-2X with 54% HFX provides the largest MAE value of 0.35 eV. The lowest obtained MAE is 0.06 eV at 23 to 25% HFX in most of the functionals considered in this study, suggesting that these are the optimal values for the prediction of excitation energies of FREAs. It has also been found that global hybrids seem to be more efficient for larger-sized molecules with a smaller bandgap.