Triplet Tuning: A Novel Family of Non-Empirical Exchange–Correlation Functionals

Lin, Zhou; Voorhis, Troy Van

doi:10.1021/acs.jctc.8b00853

Cited by 43 publications

(74 citation statements)

References 250 publications

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“…In this work, we have applied the OT and the recently proposed triplet tuning methods to study the excited states of two TADF emitters, namely, PTZ‐DBTO 2 and TAT‐3DBTO 2 . Our focus has been on the connection between each method, the performance of each in the presence of multiple excited states of different character and the geometry dependence of each method is especially relevant in the context of benchmarking multiple critical points on excited state surfaces and/or developing size‐consistent potential energy surfaces.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, Lin and Van Voorhis have proposed an alternative methodology for tuning range‐separated functionals based upon the triplet excited state energies. Indeed, the energy of the lowest electronic triplet state T 1 can be described by two means.…”

Section: Methodsmentioning

confidence: 99%

“…DFT is able to access the electronic ground of different spin symmetry (restricted DFT [rDFT] for the singlet ground state and unrestricted DFT [uDFT] for open‐shell ground states) and yields the exact energy if the exact exchange correlation functional is used. Therefore, with the knowledge of the exact exchange correlation functional, the excitation energy:

normalΔ E_{T_{1}}^{DFT} = E_{T_{1}}^{uDFT} - E_{S_{0}}^{rDFT}

where

E_{T_{1}}^{uDFT}

and

E_{S_{0}}^{rDFT}

are the energies of the triplet and singlet ground states, respectively, is exact. The other mean is to consider T 1 as the lowest triplet excited state.…”

Section: Methodsmentioning

confidence: 99%

“…and . The method has been previously tested on a range of molecular systems exhibiting low‐lying CT states . The optimal value (

ω_{J_{TT}^{2}}^{*}

) of the range‐separation parameter ω is the value that minimizes the triplet tuning function

J_{TT}^{2} ((), ω)

J_{TT}^{2} ((), ω) = {(E_{T_{1}}^{uDFT} - E_{T_{1}}^{TD ‐ DFT})}^{2} .

…”

Section: Methodsmentioning

confidence: 99%

“…Recently, Lin and Van Voorhis have proposed an alternative methodology focused upon incorporating electron–hole interactions present in excited states, which they named triplet tuning. In this work, the tuning of ω is based upon minimizing the energy difference between the lowest triplet state, calculated using unrestricted Kohn–Sham and TDDFT, which in the limit of the exact xc functional should be zero.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

On the geometry dependence of tuned‐range separated hybrid functionals

2019

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Molecules and materials that absorb and/or emit light form a central part of our daily lives. Consequently, a description of their excited-state properties plays a crucial role in designing new molecules and materials with enhanced properties. Due to its favorable balance between high computational efficiency and accuracy, time-dependent density functional theory (TDDFT) is often a method of choice for characterizing these properties. However, within standard approximations to the exchangecorrelation functional, it remains challenging to achieve a balanced description of all excited states, especially for those exhibiting charge-transfer (CT) characteristics. In this work, we have applied two approaches, namely, the optimal tuning and triplet tuning methods, for a nonempirical definition of range-separated functionals to improve the description of excited states within TDDFT. This is applied to study the CT properties of two thermally activated delayed fluorescence emitters, namely, PTZ-DBTO 2 and TAT-3DBTO 2 . We demonstrate the connection between the two methods, the performance of each in the presence on multiple excited states of different characters and the geometry dependence of each method especially relevant in the context of developing size-consistent potential energy surfaces.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

normalΔ E_{T_{1}}^{DFT} = E_{T_{1}}^{uDFT} - E_{S_{0}}^{rDFT}

where

E_{T_{1}}^{uDFT}

and

E_{S_{0}}^{rDFT}

are the energies of the triplet and singlet ground states, respectively, is exact. The other mean is to consider T 1 as the lowest triplet excited state.…”

Section: Methodsmentioning

confidence: 99%

“…and . The method has been previously tested on a range of molecular systems exhibiting low‐lying CT states . The optimal value (

ω_{J_{TT}^{2}}^{*}

) of the range‐separation parameter ω is the value that minimizes the triplet tuning function

J_{TT}^{2} ((), ω)

J_{TT}^{2} ((), ω) = {(E_{T_{1}}^{uDFT} - E_{T_{1}}^{TD ‐ DFT})}^{2} .

…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the geometry dependence of tuned‐range separated hybrid functionals

2019

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Thiocarbonyl‐Bridged N‐Heterotriangulenes for Energy Efficient Triplet Photosensitization: A Theoretical Perspective

Manna

2024

ChemPhysChem

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Rigid metal‐free organic molecules are of high demand for various triplet harvesting applications. Inefficient intersystem crossing (ISC) due to large singlet‐triplet gap ([[EQUATION]]) and small spin‐orbit coupling (SOC) between lowest excited singlet and triplet in these molecules often limits their efficiency. We computationally investigate excited‐state electronic structures, fluorescence and ISC rates in several thiiocarbonyl‐bridged N‐heterotriangulene ([[EQUATION]]S‐HTG) with systematically increased S‐content ([[EQUATION]]0‐3). All [[EQUATION]]S‐HTGs are dynamically stable and also thermodynamically feasible to synthesize. Relative energies of several low‐lying singlets ([[EQUATION]]) and triplets ([[EQUATION]]), and their excitation nature ([[EQUATION]] or [[EQUATION]]) and SOC for these [[EQUATION]]S‐HTGs in dichloromethane are determined implementing time‐dependent optimally‐tuned range‐separated hybrid. Low‐energy optical peak displays gradual red‐shift with increasing S‐content due to relatively smaller electronic gap resulted from greater degree of orbital delocalization. Significantly large SOC due to different orbital‐symmetry and heavy‐atom effect produces remarkably high ISC rates ([[EQUATION]] ~1012 s‐1) for enthalpically favoured [[EQUATION]]([[EQUATION]]) channel in these [[EQUATION]]S‐HTGs, which outcompete radiative fluorescence rates (~108 s‐1) even directly from higher lying optically bright [[EQUATION]] singlets (anti‐Kasha’s emission). Importantly, high energy triplet excitons of ~1.7 eV resulting from such significantly large ISC rates from non‐fluorescent [[EQUATION]] make these thionated molecules ideal candidates for energy efficient triplet harvest including triplet‐photosensitization.

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First principle investigations of long‐range magnetic exchange interactions via polyacene couplers

Kaur¹,

Ali²

2021

Int J of Quantum Chemistry

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The electronic and magnetic properties of polyacenes become quite fascinating as the number of linearly conjugated benzene rings increases. Higher-order conjugated polyacenes develop radicaloid characters due to the transition of electronic structures from closed-shell to the open-shell system. Here we have investigated the role of such polyacenes as the magnetic coupler when placed between the two spinsources based on nitroxy radicals. To do so, the magnetic exchange interactions (2J) are computed employing broken-symmetry (BS) approach within the density functional theory (DFT). In this approach, various genre of exchange-correlation (XC) functionals such as generalized gradient approximation (GGA), meta-GGA, hybrid functional, constrained spin density (i.e. CDFT) and on-site Coulomb correlation corrected GGA + U functionals are adopted. All DFT based calculations estimate an exponential increase in 2J values with the length of the couplers. This observation has been understood in terms of increase in number of near-degenerate or quasidegenerate molecular orbitals (MOs), reduction of HOMO-LUMO energy gap and descend of low-lying excited states as the number of fused benzene rings are increased. K E Y W O R D SDFT, intramolecular exchange interactions, long-range interactions, organic diradicals, polyacene | INTRODUCTIONMolecular magnets based on the stable organic radicals have attracted enormous attention due to their potential applications in spintronics, [1] magnetic logic devices, [2] and quantum computers. [3] The non-magnetic spacer between the radical centers control the nature and strength of intramolecular magnetic exchange interactions. [4][5][6] The seamless π-conjugations between the radical centers and spacer play a vital role in magnetic couplings. [7][8][9] Strong magnetic exchange interactions are reported mostly for couplers with smaller lengths. [10] However, the fascinating long-range couplers desired [11,12] for magnetic and spintronic applications are relatively less explored. On the top of it accomplishment of long range strong magnetic exchange interactions in molecular system is another challenge. The exchange interactions through the larger molecular spacers were investigated by Matsuda et al. for various π-conjugated couplers and established a correspondence between electrical conductance and the magnetic exchange interaction. [13] Both the molecular conductance and the exchange interactions decay exponentially with an increase in distance between radical centers. They observed that the increased π-conjugations slow down the decay process. [14,15] The strength of the magnetic exchange coupling constants (2J), mediated through π-conjugated molecular spacers was found to decay exponentially with the length of the couplers. [13] Essentially, the conductance and magnetic coupling (2J) between two spin sources are related through the molecular bridge properties. [16-18] However, in recent years interest has increased in designing and finding molecular candidates that would show an increase in

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Triplet Tuning: A Novel Family of Non-Empirical Exchange–Correlation Functionals

Cited by 43 publications

References 250 publications

On the geometry dependence of tuned‐range separated hybrid functionals

On the geometry dependence of tuned‐range separated hybrid functionals

Thiocarbonyl‐Bridged N‐Heterotriangulenes for Energy Efficient Triplet Photosensitization: A Theoretical Perspective

First principle investigations of long‐range magnetic exchange interactions via polyacene couplers

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