Computational Protocol To Predict Anti-Kasha Emissions: The Case of Azulene Derivatives

Veys, Koen; Escudero, Daniel

doi:10.1021/acs.jpca.0c05205

Cited by 48 publications

(57 citation statements)

References 82 publications

(127 reference statements)

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“…The ESs of this isomer of naphthalene were investigated in several theoretical works, 25,[86][87][88][89][90][91][92] and we have considered here six singlet ESs (four valence, two Rydberg) and four triplet ESs (all valence). We refer the interested reader to Table 1 as well as the SI for further details regarding oscillator strengths and involved MO pairs.…”

Section: Reference Values 311 Azulenementioning

confidence: 99%

A Mountaineering Strategy to Excited States: Highly Accurate Reference Energies and Benchmarks

Loos

Scemama

Blondel

et al. 2018

J. Chem. Theory Comput.

300

100

645

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Striving to define very accurate vertical transition energies, we perform both high-level coupled cluster (CC) calculations (up to CCSDTQP) and selected configuration interaction (sCI) calculations (up to several millions of determinants) for 18 small compounds (water, hydrogen sulfide, ammonia, hydrogen chloride, dinitrogen, carbon monoxide, acetylene, ethylene, formaldehyde, methanimine, thioformaldehyde, acetaldehyde, cyclopropene, diazomethane, formamide, ketene, nitrosomethane, and the smallest streptocyanine). By systematically increasing the order of the CC expansion, the number of determinants in the CI expansion as well as the size of the one-electron basis set, we have been able to reach near full CI (FCI) quality transition energies. These calculations are carried out on CC3/ aug-cc-pVTZ geometries, using a series of increasingly large atomic basis sets systematically including diffuse functions. In this way, we define a list of 110 transition energies for states of various characters (valence, Rydberg, n → π, π → π*, singlet, triplet, etc.) to be used as references for further calculations. Benchmark transition energies are provided at the aug-cc-pVTZ level as well as with additional basis set corrections, in order to obtain results close to the complete basis set limit. These reference data are used to benchmark a series of 12 excited-state wave function methods accounting for double and triple contributions, namely ADC(2), ADC(3), CIS(D), CIS(D), CC2, STEOM-CCSD, CCSD, CCSDR(3), CCSDT-3, CC3, CCSDT., and CCSDTQ. It turns out that CCSDTQ yields a negligible difference with the extrapolated CI values with a mean absolute error as small as 0.01 eV, whereas the coupled cluster approaches including iterative triples are also very accurate (mean absolute error of 0.03 eV). Consequently, CCSDT-3 and CC3 can be used to define reliable benchmarks. This observation does not hold for ADC(3) that delivers quite large errors for this set of small compounds, with a clear tendency to overcorrect its second-order version, ADC(2). Finally, we discuss the possibility to use basis set extrapolation approaches so as to tackle more easily larger compounds.

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Section: Reference Values 311 Azulenementioning

confidence: 99%

A Mountaineering Strategy to Excited States: Highly Accurate Reference Energies and Benchmarks

Loos

Scemama

Blondel

et al. 2018

J. Chem. Theory Comput.

300

100

645

View full text Add to dashboard Cite

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“…Azulene is a very well-known asymmetric isomer of naphthalene. Its electronic transitions have been investigated at various levels of theory, 149,150,177,178 likely due to its unusual non-Kasha fluorescence. According to the considered metrics, the second (2 1 ) and third (2 2 ) singlet ESs exhibit small CT characters.…”

Section: Azulenementioning

confidence: 99%

Reference Energies for Double Excitations

Loos

Boggio‐Pasqua

Scemama

et al. 2019

J. Chem. Theory Comput.

175

378

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Excited states exhibiting double excitation character are notoriously di cult to model using conventional singlereference methods, such as adiabatic time-dependent density-functional theory (TD-DFT) or equation-of-motion coupled cluster (EOM-CC). In addition, these states are typical experimentally "dark" making their detection in photo-absorption spectra very challenging. Nonetheless, they play a key role in the faithful description of many physical, chemical, and biological processes. In the present work, we provide accurate reference excitation energies for transitions involving a substantial amount of double excitation using a series of increasingly large di use-containing atomic basis sets. Our set gathers 20 vertical transitions from 14 small-and medium-size molecules (acrolein, benzene, beryllium atom, butadiene, carbon dimer and trimer, ethylene, formaldehyde, glyoxal, hexatriene, nitrosomethane, nitroxyl, pyrazine, and tetrazine). Depending on the size of the molecule, selected con guration interaction (sCI) and/or multicon gurational (CASSCF, CASPT2, (X)MS-CASPT2 and NEVPT2) calculations are performed in order to obtain reliable estimates of the vertical transition energies. In addition, coupled cluster approaches including at least contributions from iterative triples (such as CC3, CCSDT, CCSDTQ, and CCSDTQP) are assessed. Our results clearly evidence that the error in CC methods is intimately related to the amount of double excitation character of the transition. For "pure" double excitations (i.e. for transitions which do not mix with single excitations), the error in CC3 can easily reach 1 eV, while it goes down to few tenths of an eV for more common transitions (like in trans-butadiene) involving a signi cant amount of singles. As expected, CC approaches including quadruples yield highly accurate results for any type of transitions. e quality of the excitation energies obtained with multicon gurational methods is harder to predict. We have found that the overall accuracy of these methods is highly dependent of both the system and the selected active space. e inclusion of the σ and σ orbitals in the active space, even for transitions involving mostly π and π orbitals, is mandatory in order to reach high accuracy. A theoretical best estimate (TBE) is reported for each transition. We believe that these reference data will be valuable for future methodological developments aiming at accurately describing double excitations. TOC graphical abstract arXiv:1811.12861v1 [physics.chem-ph] 30 Nov 2018

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“…42 However, many instances of the breakdown of this rule has been documented. [43][44][45][46][47][48]48,49 Due to spin conservation, transition between different spin states is spin-forbidden and thus phosphorescence is usually much less intense compared to the spin-allowed counterpart. Pioneering works by Terenin, Lewis and Kasha, 50,51 led to the understanding of the electronic origin of molecular phosphorescence.…”

Section: Introductionmentioning

confidence: 99%

Behind the scenes of spin-forbidden decay pathways in transition metal complexes

Moitra

Karak

Chakraborty

et al. 2021

Phys. Chem. Chem. Phys.

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Computational Protocol To Predict Anti-Kasha Emissions: The Case of Azulene Derivatives

Cited by 48 publications

References 82 publications

A Mountaineering Strategy to Excited States: Highly Accurate Reference Energies and Benchmarks

A Mountaineering Strategy to Excited States: Highly Accurate Reference Energies and Benchmarks

Reference Energies for Double Excitations

Behind the scenes of spin-forbidden decay pathways in transition metal complexes

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