Electronic Structure and Solvation of Copper and Silver Ions:  A Theoretical Picture of a Model Aqueous Redox Reaction

Blumberger, Jochen; Bernasconi, Leonardo; Tavernelli, Ivano; Vuilleumier, Rodolphe; Sprik, Michiel

doi:10.1021/ja0390754

Cited by 201 publications

(295 citation statements)

References 57 publications

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“…Although there have been studies of electron-transfer reactions including electronic polarization in classical force-field potentials [12,13], full first-principles studies are required to describe realistically and quantitatively these reactions. Recently, an elegant grand-canonical density functional approach has been introduced to address this class of problems [14,15]. This approach is, however, targeted at half-reactions for a donor or an acceptor in contact with an electron reservoir.…”

mentioning

confidence: 99%

Realistic Quantitative Descriptions of Electron Transfer Reactions: Diabatic Free-Energy Surfaces from First-Principles Molecular Dynamics

2006

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A general approach to calculate the diabatic surfaces for electron-transfer reactions is presented, based on first-principles molecular dynamics of the active centers and their surrounding medium. The excitation energy corresponding to the transfer of an electron at any given ionic configuration (the Marcus energy gap) is accurately assessed within ground-state density-functional theory via a novel penalty functional for oxidation-reduction reactions that appropriately acts on the electronic degrees of freedom alone. The self-interaction error intrinsic to common exchange-correlation functionals is also corrected by the same penalty functional. The diabatic free-energy surfaces are then constructed from umbrella sampling on large ensembles of configurations. As a paradigmatic case study, the self-exchange reaction between ferrous and ferric ions in water is studied in detail.A wide variety of processes and reactions in electrochemistry, molecular electronics, and biochemistry have a common denominator: they involve a diabatic electron transfer process from a donor to an acceptor [1]. These reactions cover processes and applications as diverse as solar-energy conversion in the early steps of photosynthesis, oxidation-reduction reactions between a metallic electrode and solvated ions, and the I-V characteristics of molecular-electronics devices [2]. The key quantities of interest are the reaction rates (or, equivalently, the conductance) and the reaction pathways. Reaction rates, in the general scenario of Marcus theory [3,4,5], have a thermodynamic contribution (the classical Franck-Condon factor, broadly related to the free energy cost of a nuclear fluctuation that makes the donor and the acceptor levels degenerate in energy), and an electronic-structure, tunneling contribution (the LandauZener term, related to the overlap of the initial and final states).We argue in the following that state-of-the-art firstprinciples molecular dynamics calculations, together with several algorithmic and conceptual advances, are able to describe with quantitative accuracy these diabatic processes, while including the realistic description of the complex environment encountered, e.g. in nanoscale devices or at the interface between molecules and metals. Fig. 1 shows schematically an electron-transfer process and the free-energy diabatic surfaces according to the picture that was pioneered by Marcus [3,4,6,7]. In a polar solvent, the electron transfer process is mediated by thermal fluctuations of the solvent molecules. In the reactant state, the transferring electron is trapped at the donor site by solvent polarization; transfer might occur when the electron donor and acceptor sites become degenerate due to the thermal fluctuations of the solvent molecules. To characterize the role of the solvent on the electron-transfer reaction, a reaction coordinate ǫ for a given ionic configuration is introduced, as the energy dif- ference between the product and reactant state at that configuration [8]. This definition of reaction coordinate...

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confidence: 99%

Realistic Quantitative Descriptions of Electron Transfer Reactions: Diabatic Free-Energy Surfaces from First-Principles Molecular Dynamics

2006

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“…Extensions to the non-Marcus regime have been also extensively studied [240,241] and they can be easily implemented as corrections to the linear response (Marcus) picture.…”

Section: Constrained Dft and Redox Processesmentioning

confidence: 99%

“…In this process, the number of electrons in the system varies from N in the reduced state to N − 1 in the oxidized state. In practice, the method is based on the observation that the thermal distribution of vertical energy gap of the R → O+e − and O+e − → R reactions obtained through MD sampling contain all relevant information needed to compute the reaction free energy for the underlying electron transfer process [246,240]. For the half reaction in (47) this amounts to the free energy of oxidation ∆A.…”

Section: Constrained Dft and Redox Processesmentioning

confidence: 99%

Quantum modeling of ultrafast photoinduced charge separation

Rozzi

Troiani

Tavernelli

2017

J. Phys.: Condens. Matter

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Phenomena involving electron transfer are ubiquitous in nature, photosynthesis and enzymes or protein activity being prominent examples. Their deep understanding thus represents a mandatory scientific goal. Moreover, controlling the separation of photogenerated charges is a crucial prerequisite in many applicative contexts, including quantum electronics, photo-electrochemical water splitting, photocatalytic dye degradation, and energy conversion. In particular, photoinduced charge separation is the pivotal step driving the storage of sun light into electrical or chemical energy. If properly mastered, these processes may also allow us to achieve a better command of information storage at the nanoscale, as required for the development of molecular electronics, optical switching, or quantum technologies, amongst others.In this Topical review we survey recent progress in the understanding of ultrafast charge separation from photoexcited states. We report the state-of-the-art of the observation and theoretical description of charge separation phenomena in the ultrafast regime mainly focusing on molecularand nano-sized solar energy conversion systems. In particular, we examine different proposed mechanisms driving ultrafast charge dynamics, with particular regard to the role of quantum coherence and electron-nuclear coupling, and link experimental observations to theoretical approaches based either on model Hamiltonians or on first principles simulations.

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“…The hydration properties of other metal ions, in particular 3d and 4d transition metal ions [143][144][145][146][147][148][149][150][151][152], have also been the subject of numerous computational studies which have shed light on their redox properties and chemical reactivity. A representative example of this kind of work is the study, by Blumberger et al [144], of the redox reaction between copper and silver, Ag 2+ + Cu + → Ag + + Cu 2+ . To do so, they performed independent studies for both half-redox reactions, Ag 2+ + e − → Ag + and Cu + → e − + Cu 2+ , using a grand-canonical extension of AIMD [153].…”

Section: (A) Ions and Inorganic Species In Aqueous Solutionmentioning

confidence: 99%