Link atom bond length effect in ONIOM excited state calculations

Caricato, Marco; Vreven, Thom; Trucks, Gary W.; Frisch, Michael J.

doi:10.1063/1.3474570

Cited by 11 publications

(23 citation statements)

References 32 publications

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“…37 In previous studies, [35][36][37] we showed that excitation energies and properties can be accurately evaluated with ONIOM with great savings in computational cost, and that the use of link atoms does not affect the results when the model system is sensibly chosen. Despite these promising results and the simplicity of the extrapolation in Eq.…”

Section: Theorymentioning

confidence: 99%

“…[25][26][27][28][29][30][35][36][37] Hence, let us briefly review ONIOM for two layers and introduce the notation that we will use throughout the paper. Following the layer separation in Figure 1, open valencies resulting from the severing of covalent bonds are capped with link atoms (usually hydrogens), e.g., X Y −→ X-H.…”

Section: Theorymentioning

confidence: 99%

“…We showed that ONIOM can accurately reproduce excitation energies and transition properties computed at a high level of theory at a fraction of the computational cost. [35][36][37] However, a drawback of this approach is that its success depends on the correct matching of states between the subcalculations. This is relatively easy for low-lying, isolated, and bright transitions, but it becomes a significant issue if one is interested in various regions of the spectrum.…”

Section: Introductionmentioning

confidence: 99%

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Multi-state extrapolation of UV/Vis absorption spectra with QM/QM hybrid methods

Ren

Caricato

2016

The Journal of Chemical Physics

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In this work, we present a simple approach to simulate absorption spectra from hybrid QM/QM calculations. The goal is to obtain reliable spectra for compounds that are too large to be treated efficiently at a high level of theory. The present approach is based on the extrapolation of the entire absorption spectrum obtained by individual subcalculations. Our program locates the main spectral features in each subcalculation, e.g., band peaks and shoulders, and fits them to Gaussian functions. Each Gaussian is then extrapolated with a formula similar to that of ONIOM (Our own N-layered Integrated molecular Orbital molecular Mechanics). However, information about individual excitations is not necessary so that difficult state-matching across subcalculations is avoided. This multi-state extrapolation thus requires relatively low implementation effort while affording maximum flexibility in the choice of methods to be combined in the hybrid approach. The test calculations show the efficacy and robustness of this methodology in reproducing the spectrum computed for the entire molecule at a high level of theory.

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Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-state extrapolation of UV/Vis absorption spectra with QM/QM hybrid methods

Ren

Caricato

2016

The Journal of Chemical Physics

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“…This is not an issue since we showed that the excitation energies are not very sensitive to the link atom bond length. 33 The EE(L1) scheme provides the same set of embedding charges for both model system excited state calculations. In the second scheme, EE(L2), the procedure is basically the same except that two different sets of embedding charges are created for the MH and ML calculations.…”

Section: Methodsmentioning

confidence: 99%

“…One of us benchmarked ONIOM(QM:QM) for electronic transition energies and properties against a high level of theory such as the equation of motion coupled cluster singles and doubles (EOM-CCSD) method. [31][32][33] These studies showed that considerable time savings can be achieved with moderate loss in accuracy. They also showed that the use of link atoms does not affect the accuracy as long as the partitioning is sensible.…”

Section: Introductionmentioning

confidence: 99%

Point charge embedding for ONIOM excited states calculations

Biancardi

Barnes

Caricato

2016

The Journal of Chemical Physics

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Hybrid quantum mechanical methods can assist in the interpretation and prediction of the electronic spectra of large molecular structures. In this work, we study the performance of the ONIOM (Our own N-layered Integrated molecular Orbital molecular Mechanics) hybrid method for the calculation of transition energies and oscillator strengths by embedding the core region in a field of fixed point charges. These charges introduce polarization effects from the substituent groups to the core region. We test various charge definitions, with particular attention to the issue of overpolarization near the boundary between layers. To minimize this issue, we fit the charges on the electrostatic potential of the entire structure in the presence of the link atoms used to cap dangling bonds. We propose two constrained fitting strategies: one that produces an average set of charges common to both model system calculations, EE(L1), and one that produces two separate sets of embedding charges, EE(L2). The results from our tests show that indeed electronic embedding with constrained-fitted charges tends to improve the performance of ONIOM compared to non-embedded calculations. However, the EE(L2) charges work best for transition energies, and the EE(L1) charges work best for oscillator strengths. This may be an indication that fixed point charges do not have enough flexibility to adapt to each system, and other effects (e.g., polarization of the embedding field) may be necessary. Published by AIP Publishing. [http://dx

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The ONIOM method: its foundation and applications to metalloenzymes and photobiology

Chung

Hirao

et al. 2011

WIREs Comput Mol Sci

194

207

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The ONIOM (our Own N‐layer Integrated molecular Orbital molecular Mechanics) method is one of the most popular, successful, and easily‐to‐implement hybrid quantum mechanics/molecular mechanics (QM/MM) methods to treat complex molecular systems. Hybrid QM/MM methods take advantage of the high accuracy of QM methods and the low computational cost of MM methods. One key feature of the ONIOM method is a simple linear extrapolation procedure, which allows the ONIOM method to be further extended to two‐layer ONIOM(QM1:QM2), three‐layer ONIOM(QM1:QM2:MM), and, in principle, any n‐layer n‐level‐of‐theory methods. Such hierarchical features of the ONIOM method are unique among the hybrid QM/MM methods. This review article provides an overview of the theoretical foundation and recent development of the ONIOM method. Some of its recent applications to metalloenzymes and photobiology will also be highlighted. Prospective ONIOM development for more realistic simulations on the complex systems will be discussed finally. © 2011 John Wiley & Sons, Ltd.This article is categorized under: Electronic Structure Theory > Combined QM/MM Methods

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Link atom bond length effect in ONIOM excited state calculations

Cited by 11 publications

References 32 publications

Multi-state extrapolation of UV/Vis absorption spectra with QM/QM hybrid methods

Multi-state extrapolation of UV/Vis absorption spectra with QM/QM hybrid methods

Point charge embedding for ONIOM excited states calculations

The ONIOM method: its foundation and applications to metalloenzymes and photobiology

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