CCSD‐PCM Excited State Energy Gradients with the Linear Response Singles Approximation to Study the Photochemistry of Molecules in Solution

Caricato, Marco

doi:10.1002/cptc.201900152

Cited by 9 publications

(28 citation statements)

References 41 publications

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“…76 and is also close to the ADC(3)/cc-pVDZ value given by Mewes and coworkers (4.94 eV). 155 Of course, one can also found other estimates at lower levels of theory, e.g., 4.88 eV with CCSD/aug-cc-pVDZ, 196 4.73 eV with STEOM-CCSD, 144 and 4.90 eV with MRCIS(8,7)+P/ANO-DZ, 154 all three being reasonably close to the current TBE. In contrast, previous CASPT2 estimates of 4.41 eV, 172 4.51 eV, 143 4.47 eV, 173 4.45 eV 174 are all significantly too low.…”

Section: Dimethylaminobenzonitrilesupporting

confidence: 75%

“…Dimethylaminobenzonitrile (DMABN) is the prototypical system undergoing twisted intramolecular CT (TICT) and it consequently displays a dual-fluorescence signature strongly dependent on the medium. This process has been the subject of countless investigations, [62][63][64]70,[143][144][145]147,154,155,[172][173][174][184][185][186][187][188][189][190][191][192][193][194][195][196] and it is clearly not our intend to review in details all these works. Besides its TICT feature, DMABN is undoubtedly one of the most popular dye in CT benchmarks.…”

Section: Dimethylaminobenzonitrilementioning

confidence: 99%

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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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Section: Dimethylaminobenzonitrilesupporting

confidence: 75%

Section: Dimethylaminobenzonitrilementioning

confidence: 99%

Reference Energies for Double Excitations

Loos

Boggio‐Pasqua

Scemama

et al. 2019

J. Chem. Theory Comput.

175

378

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“…We developed the theory and implemented the computer code for the PTES approximation with the SS and LR formalisms in the equilibrium and non-equilibrium solvation regimes, including analytic gradients of the energy. 45,46,52,54 We will now discuss the main expressions for this series of approaches.…”

Section: Excited Statesmentioning

confidence: 99%

“…[34][35][36][37][38][39][40][41] Our contributions to this field come from the first implementation of the PCM-PTED scheme with CC with single and double excitations (CCSD-PCM-PTED) for ground and excited state properties, and from the definition of a new coupling scheme, intermediate between PTED and PTE, to maintain the cost of CC-PCM calculations virtually identical to that of in vacuo CC. [42][43][44][45][46][47][48][49][50][51][52][53][54] In fact, the main scope of this review is to discuss this new scheme, which we call "singles-T density" approximation for the correlation solvent response, or PTES. The PTES scheme includes the correlation solvent response explicitly, which is fundamental for a qualitatively correct description of the process of interest, but it avoids the PCM macro-iteration procedure that makes the PTED scheme so computationally demanding.…”

Section: Introductionmentioning

confidence: 99%

“…This body of work includes ground and excited state energy and energy gradients with the SS and LR formalisms. [44][45][46][47][48][49][50]52,54 Additionally, we discuss how this theoretical framework can be extended to polarizable MM force fields with minimal effort. 53 The review is organized as follows: Section 2 presents in detail the theory for ground and excited state CC-PCM-PTES, and how the same theoretical framework can be easily extended to polarizable MM force fields; Section 3 describes a series of applications of the CCSD-PCM schemes, and compares the accuracy with respect to experiment, and the computational cost with respect to in vacuo CC; finally, Section 4 contains an overall discussion and concluding remarks.…”

Section: Introductionmentioning

confidence: 99%

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Coupled cluster theory in the condensed phase within the singles‐T density scheme for the environment response

Caricato

2020

WIREs Comput Mol Sci

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Reliable simulations of molecules in condensed phase require the combination of an accurate quantum mechanical method for the core region, and a realistic model to describe the interaction with the environment. Additionally, this combination should not significantly increase the computational cost of the calculation compared to the corresponding in vacuo case. In this review, we describe the combination of methods based on coupled cluster (CC) theory with polarizable classical models for the environment. We use the polarizable continuum model (PCM) of solvation to discuss the equations, but we also show how the same theoretical framework can be extended to polarizable force fields. The theory is developed within the perturbation theory energy and singles-T density (PTES) scheme, where the environmental response is computed with the CC single excitation amplitudes as an approximation for the full one-particle reduced density. The CC-PTES combination provides the best compromise between accuracy and computational effort for CC calculations in condensed phase, because it includes the response of the environment to the correlation density at the same computational cost of in vacuo CC. We discuss a number of numerical applications for ground and excited state properties, based on the implementation of CC-PTES with single and double excitations (CCSD-PTES), which show the reliability and computational efficiency of the method in reproducing experimental or full-CC data.

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A mountaineering strategy to excited states: Accurate vertical transition energies and benchmarks for substituted benzenes

Loos,

Jacquemin

2024

J Comput Chem

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In an effort to expand the existing QUEST database of accurate vertical transition energies [Véril et al. WIREs Comput. Mol. Sci. 2021, 11, e1517], we have modeled more than 100 electronic excited states of different natures (local, charge‐transfer, Rydberg, singlet, and triplet) in a dozen of mono‐ and di‐substituted benzenes, including aniline, benzonitrile, chlorobenzene, fluorobenzene, nitrobenzene, among others. To establish theoretical best estimates for these vertical excitation energies, we have employed advanced coupled‐cluster methods including iterative triples (CC3 and CCSDT) and, when technically possible, iterative quadruples (CC4). These high‐level computational approaches provide a robust foundation for benchmarking a series of popular wave function methods. The evaluated methods all include contributions from double excitations (ADC(2), CC2, CCSD, CIS(D), EOM‐MP2, STEOM‐CCSD), along with schemes that also incorporate perturbative or iterative triples (ADC(3), CCSDR(3), CCSD(T)(a), and CCSDT‐3). This systematic exploration not only broadens the scope of the QUEST database but also facilitates a rigorous assessment of different theoretical approaches in the framework of a homologous chemical series, offering valuable insights into the accuracy and reliability of these methods in such cases. We found that both ADC(2.5) and CCSDT‐3 can provide very consistent estimates, whereas among less expensive methods SCS‐CC2 is likely the most effective approach. Importantly, we show that some lower order methods may offer reasonable trends in the homologous series while providing quite large average errors, and vice versa. Consequently, benchmarking the accuracy of a model based solely on absolute transition energies may not be meaningful for applications involving a series of similar compounds.

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CCSD‐PCM Excited State Energy Gradients with the Linear Response Singles Approximation to Study the Photochemistry of Molecules in Solution

Cited by 9 publications

References 41 publications

Reference Energies for Double Excitations

Reference Energies for Double Excitations

Coupled cluster theory in the condensed phase within the singles‐T density scheme for the environment response

A mountaineering strategy to excited states: Accurate vertical transition energies and benchmarks for substituted benzenes

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