Accurate Treatment of Charge-Transfer Excitations and Thermally Activated Delayed Fluorescence Using the Particle–Particle Random Phase Approximation

Al-Saadon, Rachael; Sutton, Christopher; Yang, Weitao

doi:10.1021/acs.jctc.8b00153

Cited by 13 publications

(17 citation statements)

References 64 publications

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“…36,41 Weitao Yang and coworkers also highlighted pp-RPA and its Tamm-Dancoff approximated pp-TDA variant as effective methods to compute electronic ground and excited state energies. [43][44][45][46][47][48][49][50][51][52] Starting from a doubly cationic (N-2)-electron reference, the N-electron ground state and excited states generated by excitations from the highest occupied molecular orbital (HOMO) are recovered by performing two-electron attachments. 45,[49][50] This allows the treatment of the N-electron ground and excited states on equal footing (derived as simultaneous eigenvalues of a common Hamiltonian) at a computational cost comparable to the simplest excited state methods, e.g., TDDFT/ph-RPA and configuration interaction singles (CIS).…”

Section: Introductionmentioning

confidence: 99%

“…This (N+2)-electron pp-RPA scheme and its corresponding hole-hole (hh) Tamm-Dancoff approximation (hh-TDA) were first presented by Yang and coworkers. 49 Although the pp-RPA and pp-TDA methods based on an (N-2)-electron reference have now become quite established, [43][44][45][46][47][48][49][50][51][52][53] less attention has been paid to the hh-TDA method based on an (N+2)-electron reference. Yang and coworkers applied the hh-TDA method to oxygen and sulfur atoms 49 (noting "relatively large errors" in the results), but we have found no published reports of further developments or applications of hh-TDA to molecules.…”

Section: Introductionmentioning

confidence: 99%

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Hole–hole Tamm–Dancoff-approximated density functional theory: A highly efficient electronic structure method incorporating dynamic and static correlation

Bannwarth

Hohenstein

et al. 2020

The Journal of Chemical Physics

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The study of photochemical reaction dynamics requires accurate as well as computationally efficient electronic structure methods for the ground and excited states. While time-dependent density functional theory (TDDFT) is not able to capture static correlation, complete active space self-consistent field (CASSCF) methods neglect much of the dynamic correlation. Hence, inexpensive methods that encompass both static and dynamic electron correlation effects are of high interest. Here, we revisit hole-hole Tamm-Dancoff approximated (hh-TDA) density functional theory for this purpose. The hh-TDA method is the hole-hole counterpart to the more established particle-particle TDA (pp-TDA) method, both of which are derived from the particle-particle random phase approximation (pp-RPA). In hh-TDA, the Nelectron electronic states are obtained through double annihilations starting from a doubly anionic (N+2 electron) reference state. In this way, hh-TDA treats ground and excited states on equal footing, thus allowing for conical intersections to be correctly described. The treatment of dynamic correlation is introduced through the use of commonly-employed density functional approximations to the exchange-correlation potential. We show that hh-TDA is a promising candidate to efficiently treat the photochemistry of organic and biochemical systems that involve several low-lying excited states-particularly those with both low-lying pp* and np* states where inclusion of dynamic correlation is essential to describe the relative energetics. In contrast to the existing literature on pp-TDA and pp-RPA, we employ a functional-dependent choice for the response kernel in pp-and hh-TDA, which closely resembles the response kernels occurring in linear response and collinear spin-flip TDDFT.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hole–hole Tamm–Dancoff-approximated density functional theory: A highly efficient electronic structure method incorporating dynamic and static correlation

Bannwarth

Hohenstein

et al. 2020

The Journal of Chemical Physics

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“…While many of the considerations are the same as those discussed above, ∆E ST may benefit from error cancellations if the error in S 1 and T 1 are comparable, or conversely, may exhibit a larger overall error. It is therefore unsurprising that extensive computational literature is available on the subject of predicting ∆E ST , 83,84,92,94,95 which use methods ranging from TDDFT to ROKS, with all of these works employing range-separated hybrid functionals, among other functionals.…”

Section: ∆Est In Oledsmentioning

confidence: 99%

Transition-Based Constrained DFT for the Robust and Reliable Treatment of Excitations in Supramolecular Systems

Stella¹,

Kritam²,

Genovese³

et al. 2021

Preprint

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Despite the variety of available computational approaches, state-of-the-art methods for calculating excitation energies such as time-dependent density functional theory (TDDFT), are typically computationally demanding and thus limited to moderate system sizes. Here, we introduce a new variation of constrained DFT (CDFT), implemented in the wavelet-based BigDFT code, wherein the constraint corresponds to a particular transition (T) between occupied and virtual orbitals, rather than a region of the simulation space as in traditional CDFT. In this work, we perform benchmark T-CDFT calculations for a set of gas phase acene molecules and OLED emitters and compare them to ∆SCF and TDDFT results, for different functionals and basis sets. For both classes of molecules, we find that T-CDFT based on semi-local functionals is comparable to hybrid functional results from ∆SCF and TDDFT. Furthermore, T-CDFT proves to be more robust than ∆SCF and does not suffer from the well-known problems encountered when applying TDDFT to charge-transfer (CT) states, and is therefore equally applicable to both local excitations and CT states. Finally, since T-CDFT is designed for large systems and has been implemented in linear-scaling BigDFT, it is ideally suited for exploring the effects of explicit environments on excitation energies, paving the way for future simulations of excited states in complex realistic morphologies, such as those which occur in OLED materials.

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“…15 As a result, they are employed mainly for small systems and testing purposes. 12,16,17 Besides the electronic structure method, also the description of the dielectric environment is crucial for highly polar CT states. 12,18 This is particularly important in TADF emitters, since their lowest triplet state is typically a CT with some admixture from local ππ* contributions, 12 whose balance is very sensitive to the environment's polarizability.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Surprisingly, the RSH performed much worse with an MD/RMSD of 0.66/0.70 eV, which is presumably due to the lack of any solvent model in the calculation and optimal tuning (vide supra). Further recent attempts have been made with mixed success using the particle−particle random-phase approximation (ppRPA) 16 and second-order quasi-degenerate perturbation theory. 17 Shee and Head-Gordon studied the performance of RSH functionals in combination with TD-DFT and solvent models for a set of 61 emitters, focusing on absorption and emission energies in the gas phase and different solvents rather than singlet−triplet gaps.…”

Section: ■ Introductionmentioning

confidence: 99%

PCM-ROKS for the Description of Charge-Transfer States in Solution: Singlet–Triplet Gaps with Chemical Accuracy from Open-Shell Kohn–Sham Reaction-Field Calculations

Kunze

Hansen

Grimme

et al. 2021

J. Phys. Chem. Lett.

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The adiabatic energy gap between the lowest singlet and triplet excited states ΔE ST is a central property of thermally activated delayed fluorescence (TADF) emitters. Since these states are dominated by a charge-transfer character, causing strong orbital-relaxation and environmental effects, an accurate prediction of ΔE ST is very challenging, even with modern quantum-chemical excited-state methods. Addressing this major challenge, we present an approach that combines spin-unrestricted (UKS) and restricted open-shell Kohn–Sham (ROKS) self-consistent field calculations with a polarizable-continuum model and range-separated hybrid functionals. Tests on a new representative benchmark set of 27 TADF emitters with accurately known ΔE ST values termed STGABS27 reveal a robust and unprecedented performance with a mean absolute deviation of only 0.025 eV (∼0.5 kcal/mol) and few deviations greater than 0.05 eV (∼1 kcal/mol), even in electronically challenging cases. Requiring only two geometry optimizations per molecule at the ROKS/UKS level in a compact double-ζ basis, the approach is computationally efficient and can routinely be applied to molecules with more than 100 atoms.

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Accurate Treatment of Charge-Transfer Excitations and Thermally Activated Delayed Fluorescence Using the Particle–Particle Random Phase Approximation

Cited by 13 publications

References 64 publications

Hole–hole Tamm–Dancoff-approximated density functional theory: A highly efficient electronic structure method incorporating dynamic and static correlation

Hole–hole Tamm–Dancoff-approximated density functional theory: A highly efficient electronic structure method incorporating dynamic and static correlation

Transition-Based Constrained DFT for the Robust and Reliable Treatment of Excitations in Supramolecular Systems

PCM-ROKS for the Description of Charge-Transfer States in Solution: Singlet–Triplet Gaps with Chemical Accuracy from Open-Shell Kohn–Sham Reaction-Field Calculations

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