Combined nonmetallic electronegativity equalisation and point–dipole interaction model for the frequency-dependent polarisability

Smalø, Hans S.; Åstrand, Per‐Olof; Mayer, A.

doi:10.1080/00268976.2013.797116

Cited by 15 publications

(43 citation statements)

References 85 publications

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“…In addition, the c H q * parameter increases by a factor of 200, indicating that the parameter now has a larger weight in the parametrization. There are significant changes in the carbon and hydrogen parameters as compared to our previous calibration, 36 but it seems to be a common problem in fluctuating charge models. 105 For the nitrogen parameters, two features are noted.…”

Section: Calculations and Parametrizationmentioning

confidence: 91%

“…The parameters obtained here and in our previous work 36 for C and H are given in Table 2. There are several notable differences between the carbon and hydrogen parameters 36,37,62,63,88 always been sensitive to details in the model and for an atom pair, e.g., C and H, the parameter values can be shifted between the two atom types without modifying a IJ in eq 11.…”

Section: Calculations and Parametrizationmentioning

confidence: 98%

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Complex Frequency-Dependent Polarizability through the π → π* Excitation Energy of Azobenzene Molecules by a Combined Charge-Transfer and Point-Dipole Interaction Model

et al. 2014

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The complex frequency-dependent polarizability and π → π* excitation energy of azobenzene compounds are investigated by a combined charge-transfer and point-dipole interaction (CT/PDI) model. To parametrize the model, we adopted time-dependent density functional theory (TDDFT) calculations of the frequency-dependent polarizability extended with excited-state lifetimes to include also its imaginary part. The results of the CT/PDI model are compared with the TDDFT calculations and experimental data demonstrating that the CT/PDI model is fully capable to reproduce the static polarizability as well as the π → π* excitation energy for these compounds. In particular, azobenzene molecules with different functional groups in the para-position have been included serving as a severe test of the model. The π → π* excitation is to a large extent localized to the azo bond, and substituting with electron-donating or electron-attracting groups on the phenyl rings results in charge-transfer effects and a shift in the excitation energy giving rise to azobenzene compounds with a range of different colors. In the CT/PDI model, the π → π* excitation in azobenzenes is manifested as drastically increasing atomic induced dipole moments in the azo group as well as in the adjacent carbon atoms, whereas the shifts in the excitation energies are due to charge-transfer effects.

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Section: Calculations and Parametrizationmentioning

confidence: 91%

Section: Calculations and Parametrizationmentioning

confidence: 98%

Complex Frequency-Dependent Polarizability through the π → π* Excitation Energy of Azobenzene Molecules by a Combined Charge-Transfer and Point-Dipole Interaction Model

et al. 2014

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“…Specifically, to account for the large polarizability of MNPs, (induced) charges, dipoles, and/or even multipoles would be introduced at each atom site, leading to several (polarizable) force field models for MNPs. These molecular mechanics (MM) methods include the point-dipole interaction model 38,39 (including its combination with either electronegativity equalization 40 or charge-transfer 41 ), charge-dipole interaction model, 42,43 discrete interaction model (DIM) 44,45 and its coordination-dependent variant (cd-DIM), 46 and atomic dipole approximation model. 47 These MM models can be employed in combined quantum mechanics/molecular mechanics (QM/MM) modeling of probe-MNP complexes, where the probe molecule constitutes the QM region so that its vibrational motions (in infrared and Raman spectroscopy) or electronic transitions (in fluorescence) are treated using ab initio QM theories.…”

Section: Introductionmentioning

confidence: 99%

Analytic High-Order Energy Derivatives for Metal Nanoparticle-Mediated Infrared and Raman Scattering Spectra within the Framework of Quantum Mechanics/Molecular Mechanics Model with Induced Charges and Dipoles

Pei

Mao

Shao

et al. 2022

Preprint

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This work is devoted to deriving and implementing analytic second- and third-order energy derivatives with respect to the nuclear coordinates and external electric field within the framework of the hybrid quantum mechanics/molecular mechanics method with induced charges and dipoles (QM/DIM). Using these analytic energy derivatives, one can efficiently compute the harmonic vibrational frequencies, infrared (IR) and Raman scattering (RS) spectra of the molecule in the proximity of noble metal clusters/nanoparticles. The validity and accuracy of these analytic implementations are demonstrated by the comparison of results obtained by the finite-difference method and the analytic approaches, and by the full QM and QM/DIM calculations. The complexes formed by pyridine and two sizes of gold clusters (Au18 and Au32) at varying intersystem distances of 3, 4, and 5 Å are used as the test systems, and Raman spectra of 4,40-bipyridine in the proximity of Au2057 and Ag2057 metal nanoparticles (MNP) are calculated by QM/DIM method and compared with experimental results as well. We find that the QM/DIM model can well reproduce the IR spectra obtained from full QM calculations for all the configurations, while though it properly enhances some of the vibrational modes, it artificially overestimates RS spectral intensities of several modes for the systems with very short intersystem distance. We show that this could be improved, however, by incorporating the hyperpolarizability of the gold metal cluster in the evaluation of RS intensities. Additionally, we address the potential impact of charge migration between the adsorbate and MNPs.

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“…Fig. 1(a)), multiple competing reactions may be accelerated in the same mechanochemical scenario, [91][92][93] complicating interpretation and/or computational prediction of mechanochemical phenomena. When the process in question involves, e.g., unfolding of biomolecules that are held together by weak interactions (i.e., hydrogen bonds and hydrophobic forces), brute force molecular simulations of mechanical loading 63,[94][95][96][97] or techniques, such as milestoning, that extend simulation time scales 71 may directly show what happens when a molecule is subjected to a mechanical force.…”

Section: A Which Bond Breaks First?mentioning

confidence: 99%

“…Unfortunately, because molecular energies cannot be represented as sums of pairwise (or other few-body) terms, the force distributions are not uniquely defined. 55 To avoid this difficulty, several groups have resorted to approximations (such as the harmonic approximation 103,104 or molecular mechanics force fields 92,105 ), but little evidence exists that the force distributions obtained this way (and dependent on the details of the approximation to the molecular energy) can correctly predict the weakest bonds in polyatomic molecules. Alternatively, our group showed that it is possible to define force distributions based on molecular geometries alone, 55 as well as to rigorously link such force distributions to the resulting force induced kinetics.…”

Section: A Which Bond Breaks First?mentioning

confidence: 99%

Perspective: Mechanochemistry of biological and synthetic molecules

Makarov

2016

The Journal of Chemical Physics

116

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Coupling of mechanical forces and chemical transformations is central to the biophysics of molecular machines, polymer chemistry, fracture mechanics, tribology, and other disciplines. As a consequence, the same physical principles and theoretical models should be applicable in all of those fields; in fact, similar models have been invoked (and often repeatedly reinvented) to describe, for example, cell adhesion, dry and wet friction, propagation of cracks, and action of molecular motors. This perspective offers a unified view of these phenomena, described in terms of chemical kinetics with rates of elementary steps that are force dependent. The central question is then to describe how the rate of a chemical transformation (and its other measurable properties such as the transition path) depends on the applied force. I will describe physical models used to answer this question and compare them with experimental measurements, which employ single-molecule force spectroscopy and which become increasingly common. Multidimensionality of the underlying molecular energy landscapes and the ensuing frequent misalignment between chemical and mechanical coordinates result in a number of distinct scenarios, each showing a nontrivial force dependence of the reaction rate. I will discuss these scenarios, their commonness (or its lack), and the prospects for their experimental validation. Finally, I will discuss open issues in the field.

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Combined nonmetallic electronegativity equalisation and point–dipole interaction model for the frequency-dependent polarisability

Cited by 15 publications

References 85 publications

Complex Frequency-Dependent Polarizability through the π → π* Excitation Energy of Azobenzene Molecules by a Combined Charge-Transfer and Point-Dipole Interaction Model

Complex Frequency-Dependent Polarizability through the π → π* Excitation Energy of Azobenzene Molecules by a Combined Charge-Transfer and Point-Dipole Interaction Model

Analytic High-Order Energy Derivatives for Metal Nanoparticle-Mediated Infrared and Raman Scattering Spectra within the Framework of Quantum Mechanics/Molecular Mechanics Model with Induced Charges and Dipoles

Perspective: Mechanochemistry of biological and synthetic molecules

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