Communication: Exciton analysis in time-dependent density functional theory: How functionals shape excited-state characters

Mewes, Stefanie A.; Plasser, Felix; Dreuw, Andreas

doi:10.1063/1.4935178

Cited by 86 publications

(103 citation statements)

References 46 publications

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“…To the best of our knowledge such a strategy has never been used for excited state analysis. [5,[59][60][61][62][63] Computations were performed on the oligomer containing six thiophene units (OT6) using TDDFT in the Tamm-Dancoff approximation [64][65][66] with the CAM-B3LYP functional [67][68][69] and Ahlrichs' SV(P) basis set. Practically, W AB and 1 h:A e are evaluated in the spirit of a Löwdin population analysis, [56][57][58] see Section S1 of the Supporting Information (SI) for details.…”

Section: Felix Plasser* [A]mentioning

confidence: 99%

Visualisation of Electronic Excited‐State Correlation in Real Space

Plasser

2019

ChemPhotoChem

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A method for the visualisation of excited-state electron correlation is introduced and shown to address two notorious problems in excited-state electronic structure theory, the analysis of excitonic correlation and the distinction between covalent and ionic wavefunction character. The method operates by representing the excited state in terms of electron and hole quasiparticles, fixing the hole on a fragment of the system and observing the resulting conditional electron density in real space. The application of this approach to oligothiophene, an exemplary conjugated polymer, illuminates excitonic correlation effects of its excited states in unprecedented clarity and detail. A study of naphthalene shows that the distinction between the ionic and covalent states of this molecule, which has so far only been achieved using elaborate valence-bond theory protocols, arises naturally in terms of electron-hole avoidance and enhanced overlap, respectively. More generally, the method is relevant for any excited state that cannot be described by a single electronic configuration.Electronically excited states of molecules form the underpinnings of a wide range of processes of utmost scientific interest, such as light-driven natural processes [1,2] photochemical reactions, [3] signalling and sensing, [4] and the operation of organoelectronic materials. [5,6] Computational photochemistry has become an indispensable part of scientific investigations in these areas through two main tasks, the interpretation of experimental results and the prediction of unknown photophysical properties. Indeed, the predictive power of computational photochemistry has steadily increased over the recent years due to the tremendous effort spent in the development of new methods as well as rapid progress in computer technology. [7][8][9][10][11][12] However, the interpretation of this wealth of computational data can act as a significant impediment in practical work. Therefore, a number of analysis tools have been developed to quantify excited-state properties [13][14][15][16][17] and to visualise the molecular orbitals (MOs) involved and their location in space in a compact and rigorous way. [18][19][20][21][22][23] However, the above-mentioned visualisation tools -and the MO picture itself -break down if the information of interest does not lie in the MOs themselves but in the interaction of different quasidegenerate electronic configurations. Such cases are widespread and two notorious failures of the MO picture relate to excitons in extended systems [24][25][26] and to ionic/ covalent wavefunction character in alternant hydrocarbons. [27,28] The first case is related to the emergence of band structure in large systems, which leads to excited states formed as a superposition of many different electronic configurations whose description requires moving from the MO picture to a representation in terms of correlated electron and hole quasiparticles. [26,[29][30][31] Previous attempts of visualising the ensuing correlated electron-hole distribution ha...

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Section: Felix Plasser* [A]mentioning

confidence: 99%

Visualisation of Electronic Excited‐State Correlation in Real Space

Plasser

2019

ChemPhotoChem

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“…Linear response TD‐DFT calculations have been performed using the long‐range separated functional CAMY‐B3LYP in combination with the TZ2P basis set, no FC, with ZORA scalar‐relativistic effect, and with and without nonequilibrium COSMO (DCM) to simulate the DCM solvent environment. For molecules showing excitations with a charge‐transfer nature, long‐range separated functionals exhibit the correct asymptotic nature and thus can successfully predict excitation energies . In addition, extensive benchmarks have been performed earlier by the groups of Tozer and Kronik where they highlighted the ability of the range‐separated functional CAM‐B3LYP to accurately predict various types of excitations in organic dye molecules, in particular, charge‐transfer excitation .…”

Section: Computational Detailsmentioning

confidence: 99%

Rational design of near‐infrared absorbing organic dyes: Controlling the HOMO–LUMO gap using quantitative molecular orbital theory

et al. 2018

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Principles are presented for the design of functional near‐infrared (NIR) organic dye molecules composed of simple donor (D), spacer (π), and acceptor (A) building blocks in a D‐π‐A fashion. Quantitative Kohn–Sham molecular orbital analysis enables accurate fine‐tuning of the electronic properties of the π‐conjugated aromatic cores by effecting their size, including silaaromatics, adding donor and acceptor substituents, and manipulating the D‐π‐A torsional angle. The trends in HOMO–LUMO gaps of the model dyes correlate with the excitation energies computed with time‐dependent density functional theory at CAMY‐B3LYP. Design principles could be developed from these analyses, which led to a proof‐of‐concept linear D‐π‐A with a strong excited‐state intramolecular charge transfer and a NIR absorption at 879 nm. © 2018 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc.

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“…[41] based on considering the overlaps of molecular orbital moduli, and more recently the ∆r-index, based on the charge-centroids of the orbitals involved in the transition [42]. The particle-hole map, related to the transition-density map, gives a direct visualization of the origin and destination of electrons and holes for a given excitation, so can indicate the role of charge-transfer for that excitation [43,44].…”

Section: A Charge-transfer Between Closed-shell Fragmentsmentioning

confidence: 99%

Charge transfer in time-dependent density functional theory

Maitra

2017

J. Phys.: Condens. Matter

139

151

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Charge transfer plays a crucial role in many processes of interest in physics, chemistry, and biochemistry. In many applications the size of the systems involved calls for time-dependent density functional theory (TDDFT) to be used in their computational modeling, due to its unprecedented balance between accuracy and efficiency. However, although exact in principle, in practise approximations must be made for the exchange-correlation functional in this theory, and the standard functional approximations perform poorly for excitations which have a long-range charge-transfer component. Intense progress has been made in developing more sophisticated functionals for this problem, which we review. We point out an essential difference between the properties of the exchange-correlation kernel needed for an accurate description of charge-transfer between open-shell fragments and between closed-shell fragments. We then turn to charge-transfer dynamics, which, in contrast to the excitation problem, is a highly non-equilibrium, non-perturbative, process involving a transfer of one full electron in space. This turns out to be a much more challenging problem for TDDFT functionals. We describe dynamical step and peak features in the exact functional evolving over time, that are missing in the functionals currently used. The latter underestimate the amount of charge transferred and manifest a spurious shift in the charge transfer resonance position. We discuss some explicit examples.

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Communication: Exciton analysis in time-dependent density functional theory: How functionals shape excited-state characters

Cited by 86 publications

References 46 publications

Visualisation of Electronic Excited‐State Correlation in Real Space

Visualisation of Electronic Excited‐State Correlation in Real Space

Rational design of near‐infrared absorbing organic dyes: Controlling the HOMO–LUMO gap using quantitative molecular orbital theory

Charge transfer in time-dependent density functional theory

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