A rigorous nonorthogonal configuration interaction approach for the calculation of electronic couplings between diabatic states applied to singlet fission

Wibowo, Meilani; Broer, Ria; Havenith, Remco W. A.

doi:10.1016/j.comptc.2017.03.013

Cited by 29 publications

(33 citation statements)

References 23 publications

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“…More recently, Wibowo et al. improved the NOCI method by allowing orbital relaxation for each state . They employed this method to evaluate the effective eg ( ge )– tt couplings for the model chromophore designed by Akdag et al.…”

Section: Exploration For Singlet Fission Mechanisms Through Electronimentioning

confidence: 99%

Theoretical Studies of Singlet Fission: Searching for Materials and Exploring Mechanisms

2018

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In this Review article, a survey is given for theoretical studies in the subject of singlet fission. Singlet fission converts one singlet exciton to two triplet excitons. With the doubled number of excitons and the longer lifetime of the triplets, singlet fission provides an avenue to improve the photoelectric conversion efficiency in organic photovoltaic devices. It has been a subject of intense research in the past decade. Theoretical studies play an essential role in understanding singlet fission. This article presents a Review of theoretical studies in singlet fission since 2006, the year when the research interest in this subject was reignited. Both electronic structure and dynamics studies are covered. Electronic structure studies provide guidelines for designing singlet fission chromophores and insights into the couplings between single‐ and multi‐excitonic states. The latter provides fundamental knowledge for engineering interchromophore conformations to enhance the fission efficiency. Dynamics studies reveal the importance of vibronic couplings in singlet fission.

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Section: Exploration For Singlet Fission Mechanisms Through Electronimentioning

confidence: 99%

Theoretical Studies of Singlet Fission: Searching for Materials and Exploring Mechanisms

2018

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“…This balanced treatment of static and dynamical correlation is particularly important in our application to the oligoacenes, or n-acenes for n linearly fused benzene rings. The oligoacenes have long been of fundamental interest to chemists due to their semiconducting and optical properties, [54][55][56][57][58][59][60][61][62][63][64] and theoreticians have been studying their singlet-triplet splittings and ground state electronic structures with particular attention to the disputed emergence of a stable, open-shell singlet ground state with increasing acene size. 12,22,54,[65][66][67][68][69][70][71][72][73][74][75][76] In characterizing the ground state, qualitatively different interpretations can arise depending on the degree dynamical correlation included, with recent studies suggesting that pure active-space methods tend to overestimate biradical character in these ground states.…”

Section: The Oligoacenesmentioning

confidence: 99%

A Combined Selected Configuration Interaction and Many-Body Treatment of Static and Dynamical Correlation in Oligoacenes

Schriber

Hannon

et al. 2018

J. Chem. Theory Comput.

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We have combined our adaptive configuration interaction (ACI) [J.B. Schriber and F.A. Evangelista, J. Chem. Phys. 144, 161106 (2016)] with a density-fitted implementation of the second-order perturbative multireference driven similarity renormalization group (DSRG-MRPT2) [K.P. Hannon, C. Li and F.A. Evangelista J. Chem. Phys. 144, 204111 (2016)]. We use ACI reference wave functions to recover static correlation for active spaces larger than the conventional limit of 18 orbitals. The dynamical correlation is computed using the DSRG-MRPT2 to yield a complete treatment of electron correlation. We apply the resulting method, ACI-DSRG-MRPT2, to predict singlet-triplet gaps, metrics of open-shell character, and spin-spin correlation functions for the oligoacene series (2-7 rings). Our computations employ active spaces with as many as 30 electrons in 30 orbitals and up to 1350 basis functions, yielding gaps that are in good agreement with available experimental results. Large bases and reference relaxation lead to a significant reduction in the estimated radical character of the oligoacenes with respect to previous valence-only treatments of correlation effects.

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“…Theoretical studies have been performed in order to find new SF molecules that fulfill the critical energetic criteria E(S 1 ) > 2E(T 1 ), [12,13] and also to understand its underlying mechanism (a detailed review can be found in Ref. [14]) but many questions of how this process actually occurs are still active areas of research; these include the role of the vibrational modes [15][16][17][18][19] and charge transfer (CT) states [20,21] in the SF process.…”

Section: Introductionmentioning

confidence: 99%

Singlet fission in tetracene: an excited state analysis

2020

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Singlet fission is a potential mechanism to enhance the performance of current solar cells. However, the actual mechanism is still a matter of debate, with charge transfer states believed to play an essential role. The probability of the overall process can be related to the electronic coupling between the electronic states. Here, we explore the excited states of three pairs of tetracene with different relative orientation in the crystal structure showing different electronic couplings and identify the role of charge transfer states. First, a suitable theoretical method for the study of the tetracene pairs is determined by comparing time-dependent density functional theory with wave function-based methods in terms of excitation energies, so-called exciton descriptors, and graphical tools such as electron-hole correlation plots and natural transition orbitals. The results show the presence of lowlying charge transfer states in those tetracene pairs with non-zero electronic coupling, suggesting a superexchange-mediated mechanism, and high-lying charge resonance states for the pair with zero electronic coupling. Finally, the lower electron-hole correlation coefficients for pairs with non-zero coupling speak in favour of the superexchange-mediated mechanism, as a weaker Coulombic attraction due to the mixing with charge transfer states further facilitates the formation of the 1 TT state from the photoexcited molecule.

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A rigorous nonorthogonal configuration interaction approach for the calculation of electronic couplings between diabatic states applied to singlet fission

Cited by 29 publications

References 23 publications

Theoretical Studies of Singlet Fission: Searching for Materials and Exploring Mechanisms

Theoretical Studies of Singlet Fission: Searching for Materials and Exploring Mechanisms

A Combined Selected Configuration Interaction and Many-Body Treatment of Static and Dynamical Correlation in Oligoacenes

Singlet fission in tetracene: an excited state analysis

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