Efficient enumeration of bosonic configurations with applications to the calculation of non-radiative rates

Shaw, Robert A.; Manian, Anjay; Lyskov, Igor; Russo, Salvy P.

doi:10.1063/5.0039532

Cited by 6 publications

(23 citation statements)

References 36 publications

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“…Here, a similar framework has been implemented. We have recently published a number of viable methods for computation of such bosonic configurations beyond just the maximum 32 , and will illustrate how it is employed further in this study, as well as present an open source code which allows for ready replication of our methods. This will be discussed in more detail later.…”

Section: Please Cite This Article As Doi:101063/50058643mentioning

confidence: 99%

“…Ref. 32 outlines three possible solutions. The first is a brute force scan; testing every plausible configuration within the CS.…”

Section: Configuration Space Computationmentioning

confidence: 99%

“…The resulting HR factors and their corresponding energies have been reported within the SI. Scanning of the CS and computation of the IC rate constant was performed using the Knapsack software package 32 .…”

Section: Configuration Space Computationmentioning

confidence: 99%

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Modeling radiative and non-radiative pathways at both the Franck–Condon and Herzberg–Teller approximation level

Manian¹,

Shaw

Lyskov³

et al. 2021

The Journal of Chemical Physics

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Here, we present a concise model which can predict the photoluminescent properties of a given compound from first principles, both within and beyond the Franck-Condon approximation. The formalism required to compute fluorescence, Internal Conversion (IC), and Inter-System Crossing (ISC) is discussed. The IC mechanism in particular is a difficult pathway to compute due to difficulties associated with the computation of required bosonic configurations and non-adiabatic coupling elements. Here, we offer a discussion and breakdown on how to model these pathways at the Density Functional Theory (DFT) level, with respect to its computational implementation, strengths and current limitations. The model is then used to compute the photoluminescent quantum yield (PLQY) of a number of small but important compounds: Anthracene, Tetracene, Pentacene, diketo-pyrrolo-pyrrole (DPP), and Perylene Diimide (PDI), within a polarizable continuum model. Rate constants for fluorescence, IC, and ISC compare well for the most part with respect to experiment, despite triplet energies being overestimated to a degree. The resulting PLQYs are promising with respect to the level of theory being DFT. While we obtained a positive result for PDI within the Franck-Condon limit, the other systems require a second order correction. Recomputing quantum yields with Herzberg-Teller terms yields PLQYs of 0.19, 0.08, 0.04, 0.70, and 0.99 for Anthracene, Tetracene, Pentacene, DPP, and PDI respectively. Based on these results, we are confident the presented methodology is sound with respect to the level of quantum chemistry, and presents an important stepping stone in the search for a tool to predict properties of larger, coupled systems.

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Section: Please Cite This Article As Doi:101063/50058643mentioning

confidence: 99%

“…Ref. 32 outlines three possible solutions. The first is a brute force scan; testing every plausible configuration within the CS.…”

Section: Configuration Space Computationmentioning

confidence: 99%

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Modeling radiative and non-radiative pathways at both the Franck–Condon and Herzberg–Teller approximation level

Manian¹,

Shaw

Lyskov³

et al. 2021

The Journal of Chemical Physics

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“…Internal conversion (IC) is a nonradiative relaxation pathway that occurs when an exciton transitions between two same-spin states. − Mediated by nonadiabatic (or vibronic) coupling, this mechanism is computationally expensive to treat, because of a required analysis of bosonic configurations for each state of interest. , Frustratingly, no known polynomial-time algorithm offers an exact solution . As such, one must enumerate every possible configuration, with respect to some satisfactory energy condition, until a complete configuration space (CS) describing all nonzero contributing configurations is generated.…”

Section: Introductionmentioning

confidence: 99%

“…Over the previous decades, a large body of work as been dedicated toward optimizing these processes. Works combining the efforts of Plotnikov, Robinson, and Jortner via the Intermediate Neglect of Differential Overlap (INDO) method yielded positive results. − Following, this methodology was combined with time-dependent density functional theory (TDDFT) to yield much more accurate rate constant calculations directly from first principles. ,, Recently, we developed a method to compute these complex CSs in an application toward the Plotnikov–Robinson–Jortner (PRJ) formalism, before applying it to several small but important chromophores . Sticking with DFT-based methods, we were able to compute very appreciable rate constants and corresponding photoluminescence quantum yields (PLQYs), with respect to experimental results, where the PLQY is defined as the probability that a molecule will radiate upon photorelaxation.…”

Section: Introductionmentioning

confidence: 99%

Exciton Dynamics of a Diketo-Pyrrolopyrrole Core for All Low-Lying Electronic Excited States Using Density Functional Theory-Based Methods

Manian

Shaw

Lyskov

et al. 2022

J. Chem. Theory Comput.

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Ab initio treatments of interexcited state internal conversion (IC) are more often than not missing from exciton dynamic descriptions, because of their inherent complexity. Here, we define "interexcited state IC" as a same-spin nonradiative transition between states i and j, where i ≠ j ≠ 0. Competing directly with multiexciton processes such as singlet fission or triplet photoupconversion, inclusion of this mechanism in the narrative of molecular photophysics would allow for strategic synthesis of chromophores for more efficient photon-harvesting applications. Herein, we present a robust formalism which can model these rates using density functional theory (DFT)-based methods within the Franck−Condon and Herzberg−Teller regime. Using an unsubstituted diketopyrrolopyrrole (DPP) core as a case study, we illustrate the exciton dynamics along the first four excited states for both singlet and triplet manifolds, showing ultrafast same-spin transfer mechanisms due to all excited states, excluding the first triplet level, being in close energetic proximity (within 0.8 eV of each other). The resulting electron same-spin rates outcompete the electron spin-flipping intersystem crossing (ISC) rates, with excitons firmly obeying Kasha's rule as they cascade down from the high-lying excited states toward the lower states. Furthermore, we calculated that only the first singlet excited state displayed a reasonable probability of triplet exciton generation, of ∼40%, with a near-zero chance of the exciton reverting to the singlet manifold once the electron−hole pair are of parallel spin.

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Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers

Manian,

Campaioli,

Hudson

et al. 2023

Chem. Mater.

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The role of charge transfer states in multi-exciton mechanisms has recently become a point of discussion due to the difficulty associated with modeling their contributions accurately. Intermolecular packing has been shown experimentally to heavily influence multi-exciton mechanisms, and therefore understanding how this affects the coupling is key to controlling these processes. Using a gas phase perylene dimer in a weakly coupled configuration as a case study, we employ two separate methods to model the coupling between the bright and correlated triplet 1 TT states as a function of relative displacement. For singlet fission, displaced geometries are found to yield large charge transfer contributions within a wavefunction overlap paradigm, unlike for aligned geometries. Triplet−triplet annihilation charge transfer couplings are conversely very weak due to a large energy gap. We found that slipping of the dimer cofacial geometry is beneficial to both charge transfer-mediated processes within a wavefunction overlap scheme. However, within a fragment excitation difference (FED) scheme, a 1 Å slip is more beneficial than a 2 Å one. The resulting rates for singlet fission are in the femtosecond range, up to 22 ps −1 , while for triplet fusion they are in the nanosecond range, up to 707 μs −1 . By studying the dynamics of the triplet pair following singlet fission, we show that the decorrelation time scale depends on the nature of the relative molecular motion, ranging from picoseconds for fluctuations in the monomer orientations to microseconds for coplanar fluctuations. The direct comparison of the wavefunction overlap and FED methods yields an expected differential due to the method of calculation (linear-response vs multireference) but still strong agreement, suggesting that the more exact wavefunction overlap method can be substituted for the FED method in larger systems with minimal loss in accuracy vs computational complexity. These results provide a good stepping stone for further investigations into singlet fission related problems, correlating well with experiments despite the weakly coupled nature of the dimer.

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Efficient enumeration of bosonic configurations with applications to the calculation of non-radiative rates

Abstract: This is a repository copy of Efficient enumeration of bosonic configurations with applications to the calculation of non-radiative rates.

Cited by 6 publications

References 36 publications

Modeling radiative and non-radiative pathways at both the Franck–Condon and Herzberg–Teller approximation level

Modeling radiative and non-radiative pathways at both the Franck–Condon and Herzberg–Teller approximation level

Exciton Dynamics of a Diketo-Pyrrolopyrrole Core for All Low-Lying Electronic Excited States Using Density Functional Theory-Based Methods

Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers

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