Optical Properties of Gold Nanoclusters Functionalized with a Small Organic Compound: Modeling by an Integrated Quantum-Classical Approach

“…This methodology has proven to be efficient and sound because it relies on both quantum calculations and experimental data (which were included in the training sets) and on features, such as polarizable charges, continuous energy definition, bond breaking, formation, etc., that enable it to outline the properties of hierarchical materials as accurately as quantum chemistry methods and refined experimental techniques. Moreover, ReaxFF parametrization of gold nanoparticles and their interactions with various types of systems was already tested in a number of previous investigations [30][31][32] and recently improved to simulate the spectroscopic properties of para-nitro-aniline (pNA) on different facets of variously sized AuNPs, 33 in connection with the hybrid quantum mechanics/ capacitance molecular mechanics (QM/CMM) method. [34][35][36][37] Computational details…”

Section: Introductionmentioning

confidence: 99%

Decoration of gold nanoparticles with cysteine in solution: reactive molecular dynamics simulations

2016

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The dynamics of gold nanoparticle functionalization by means of adsorption of cysteine molecules in water solution is simulated through classical reactive molecular dynamics simulations based on an accurately parametrized force field. The adsorption modes of the molecules are characterized in detail disclosing the nature of the cysteine-gold interactions and the stability of the final material. The simulation results agree satisfactorily with recent experimental and theoretical data and confirm previous findings for a similar system. The covalent attachments of the molecules to the gold support are all slow physisorptions followed by fast chemisorptions. However, a great variety of binding arrangements can be observed. Interactions with the adsorbate caused surface modulations in terms of adatoms and dislocations which contributed to strengthen the cysteine adsorption.

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“…We also recall that the introduction of induced dipoles requires to re-parameterize the permanent charges with respect to the values used in an electrostatic embedding scheme. Atomistic descriptions of metal nanoparticles (DIM and connected approaches) 82,84 closely follow this scheme as well. The most notable differences are that (i) the atomic polarizability becomes frequency dependent and a complex number, encoding in the imaginary part the dissipation of light by the metal (see box 4) and (ii) some versions of the approach include also the possibility that each atom develops a net charge.…”

Section: Boxmentioning

confidence: 97%

“…Various prescriptions have been given to set the metal atom parameters of this model, that in the most recent version depend also on the coordination environment of the metal atom. Similar models have been also incorporated in other descriptions, such as the capacitance-polarization model proposed by Rinkievicius et al 84 . Moreover, proper metal-solvent-molecule force fields are being developed to include a proper sampling of the ground state geometries.…”

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confidence: 99%

Multiscale modelling of photoinduced processes in composite systems

2019

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| In the last decades, the quantum mechanical modeling has moved from isolated molecules made of few atoms, to large supramolecular aggregates embedded in complex environments. This has been made possible by the important progress achieved by multiscale models based on the integration of QM methods with classical descriptions. One of the first example of this integration is represented by continuum solvation models that starting from the eighties of the last century have been largely and successfully applied to predict properties and processes of solvated molecules. Almost in the same years, another alternative classical description, based on Molecular Mechanics (MM) has been coupled to QM methods to give the hybrid QM/MM approach. Since their first formulations, these QM/classical models have seen an enormous development in terms of accuracy, robustness and generalizability. This progress has allowed their application to systems of increasing complexity and to processes never faced before within a QM framework. An important example of such an achievement is represented by the novel insights reached in the fundamental understanding and the possible exploitation of photoinduced processes in biomolecules, nanomaterials and, more in general, composite systems where different "objects" of molecular, nano and mesoscopic scale are coupled together. In this review, we highlight the potentials and the limitations of such modeling, thereby showing which developments are still needed to definitely make the QM-based multiscale strategy the gold-standard for explaining the outputs of novel advanced spectroscopic techniques and predicting the outcome of light-activated events in composite systems. The multiscale strategiesIn the years, two main strategies to combine QM descriptions of the target and classical models of the environment, have been proposed. Interestingly, their first formulations date back to the same years, namely the end of the seventies of the previous century. [8][9][10] The two strategies refer to continuum and discrete (or atomistic) descriptions of the environment, respectively. In the latter case, the atoms of the environment (or group of atoms in coarser grained versions of the model) are treated through a Molecular Mechanics (MM) force field (FF). [11][12][13][14][15] In the former case, instead, the atomic nature of the environment is lost and a continuum description in terms of macroscopic properties is introduced instead. 16-18 Despite this huge "modellistic" difference, the two formulations present important common elements when reconsidered from the point of view of the QM target. In any case, for simplicity's sake two separate presentations will be given. QM/continuum. If the environment loses its atomic nature, an effective description has to be introduced which is based on some macroscopic properties. This is exactly what is done in continuum models where the target sees the environment as an infinite dielectric medium characterized by a (generally) frequency and position dependent permittivit...

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Optical Properties of Gold Nanoclusters Functionalized with a Small Organic Compound: Modeling by an Integrated Quantum-Classical Approach

Cited by 9 publications

References 66 publications

Characterization of the adsorption dynamics of trisodium citrate on gold in water solution

Characterization of the adsorption dynamics of trisodium citrate on gold in water solution

Decoration of gold nanoparticles with cysteine in solution: reactive molecular dynamics simulations

Multiscale modelling of photoinduced processes in composite systems

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