Erratum: The theory of the Fe2+–Fe3+ electron exchange in water [J. Chem. Phys. <b>7</b>
                  <b>6</b>, 1490 (1982)]

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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“…5.5Å was suggested [4,30] to be the optimal distance for electron transfer. We show our results in Fig.…”

mentioning

confidence: 99%

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

2006

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“…Data for cadmium relaxed by Mn(II) ion are shown in Fig. 10 which was motivated by the interest in defining the characteristics of like-charge ion pairs thought to be important in a variety of contexts, particularly electron transfer reactions (17)(18)(19). We have observed complex formation between lithium ion and manganese(II) ion (20) and were interested in whether one may observe ion pairing interactions between a 2ϩ ion and a 2ϩ ion.…”

Section: Example Solute Dispersionsmentioning

confidence: 97%

High-Resolution Magnetic Relaxation Dispersion Measurements of Solute Spin Probes Using a Dual-Magnet System

Wagner

Dinesen

Rayner

et al. 1999

Journal of Magnetic Resonance

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“…A distance of 5.5 A was suggested [4,43] as optimal for electron transfer. The initial configuration for the simulations were prepared by carving out two spheres, each containing seven water molecules, from the last configuration of a wellequilibrated 64-water-molecule simulation at 400 K and replacing them by two hexaaqua iron ions, 5.5 A apart.…”

Section: Diabatic Free-energy Surfaces When Two Ions Are At a Finite mentioning

confidence: 99%

“…The two groups are the localized D and A species, whose structural identity is maintained throughout the (outer-sphere) reaction [61]. The D and A groups are assumed to be in contact around the transition state, at the ET optimal interionic distance of 5.5 A [4,11,14,16,43]. The transfer integrals are computed for selected nuclear configurations along a Car-Parrinello MD (CPMD) run from Reference 14; the timestep is 5 au and the selected snapshots are 3000 steps apart (%0.36 ps).…”

Section: Transfer Integralsmentioning

confidence: 99%

Quantitative Description of Electron Transfer Reactions

et al. 2010

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Erratum: The theory of the Fe2+–Fe3+ electron exchange in water [J. Chem. Phys. 7 6, 1490 (1982)]

Cited by 17 publications

References 1 publication

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

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

High-Resolution Magnetic Relaxation Dispersion Measurements of Solute Spin Probes Using a Dual-Magnet System

Quantitative Description of Electron Transfer Reactions

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