Redox Levels through Constant Fermi-Level ab Initio Molecular Dynamics

Bouzid, Assil; Pasquarello, Alfredo

doi:10.1021/acs.jctc.6b01232

Cited by 27 publications

(34 citation statements)

References 71 publications

(121 reference statements)

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“…48 Promisingly, some studies suggest that the slower charge dynamics and equilibration of the potential following a variation of the system electron count only modestly increases the overall computational cost. 49 Although the issue of how to correctly model the compensating counter-charge remains unresolved, these proceedings bear the promise of revoking the need for post hoc correction of canonical simulations to approximate grand canonical conditions in future studies.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Reconciling the Experimental and Computational Hydrogen Evolution Activities of Pt(111) through DFT-Based Constrained MD Simulations

Kronberg

Laasonen

2021

ACS Catal.

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The computational hydrogen evolution activity of Pt(111) remains controversial due to apparent discrepancies with experiments concerning rate-determining activation free energies and equilibrium hydrogen coverages. A fundamental source of error may lie within the static representations of the metal−water interface commonly employed in density functional theory (DFT)based kinetic models neglecting important entropic effects on reaction dynamics. In this work, we present a dynamic reassessment of the Volmer−Tafel hydrogen evolution pathway on Pt(111) through DFT-based constrained molecular dynamics simulations and thermodynamic integration. Hydrogen coverage effects are gauged at two distinct surface saturations, while the critical potential dependence and constant potential conditions are accounted for using a capacitive model of the electrified interface. The uncertainty in the highly nontrivial treatment of the electrode potential is carefully examined, and we provide a quantitative estimation of the error associated with dynamically simulated electrochemical barriers. The dynamic description of the electrochemical interface promotes a substantial decrease of the Tafel free energy barrier as the coverage is increased to a full monolayer. This follows from a decreased entropic barrier due to suppressed adlayer dynamics compared to the unsaturated surface, a detail easily missed by static calculations predicting notably higher barriers at the same coverage. Due to observed endergonic adsorption of active hydrogen intermediates, the Tafel step remains ratedetermining irrespective of the coverage as illustrated by composed Volmer−Tafel free energy landscapes. Importantly, our explicitly dynamic approach avoids the ambiguous choice of frozen solvent configuration, decreasing the reliance on error cancellation and paving the way for less biased electrochemical simulations.

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Section: Theoretical Methodsmentioning

confidence: 99%

Reconciling the Experimental and Computational Hydrogen Evolution Activities of Pt(111) through DFT-Based Constrained MD Simulations

Kronberg

Laasonen

2021

ACS Catal.

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“…27,28,[30][31][32][33][34]. (Other constant electrode potential simulation techniques including, e.g., constant Fermi-level simulations 35,36 , are being developed but require much more computationally demanding explicit electronic structure calculations; recently developed 37 classical polarizable potentials for metals based on the embedded atom method can also be combined with the Siepmann and Sprik extended Lagrangian and would be a promising route to describe constant potential electrodes.) These classical simulations were shown 15 to provide descriptions of interfacial water structure 24 and water sum-frequency generation spectra 38 in very good agreement with DFT-based simulations, while allowing the propagation of long trajectories required for our dynamical analysis.…”

Section: Methodsmentioning

confidence: 99%

Water dynamics at electrified graphene interfaces: a jump model perspective

Zhang

Stirnemann

Hynes

et al. 2020

Phys. Chem. Chem. Phys.

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“…With this choice of alignment, the conduction band minimum and the valence band maximum of liquid water occur at −2.5 and 1.7 eV, respectively. A complete description of the computational setup is provided in ref [29].…”

Section: Cfl-md In Aqueous Solution: Determination Of Redox Levelsmentioning

confidence: 99%

Atomic‐Scale Modelling of Electrochemical Interfaces through Constant Fermi Level Molecular Dynamics

Bouzid

Pasquarello

2021

Atomic‐Scale Modelling of Electrochemical Systems

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Electrochemical reactions involving electron/proton transfer occur in several technologically relevant environments, such as solar cells, energy conversion, and storage devices. In these systems, the electron/proton transfer is governed by the applied bias potential and leads to the occurrence of complex electrochemical reactions. While experiments provide access to most of the macroscopic electrochemical properties of these reactions, they are unable to describe the electrochemical processes occurring at the atomic scale. At this level, modelling electrochemical processes either in solution or at metal interfaces is of paramount importance towards a full control and understanding of reaction mechanisms occurring under applied bias potential. Several techniques have been developed to study systems under bias potential in combination with ab initio molecular dynamics and advanced electronic structure techniques. Among them, constant Fermi level ab initio molecular dynamics (CFL-MD) is emerging as a promising and efficient scheme. In this Chapter, we focus on the constant Fermi level molecular dynamics technique and present some applications to electrochemistry. In the methods section, we provide a detailed review of the constant Fermi level ab initio molecular dynamics technique. Then, we illustrate the performance of CFL-MD in determining redox levels of half reactions in solution. In particular, we show that redox half-reactions can be driven by varying the Fermi level within the electronic gap of liquid water, thereby revealing reaction mechanisms without any prior knowledge of the reaction products. On the basis of Janak's theorem, we derive a scheme for determining redox potentials from the evolution of single-particle energy levels upon charging (or discharging) the system. For the considered redox couples, the calculated redox levels are found to agree closely with those obtained via the thermodynamic integration method. The agreement with

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Redox Levels through Constant Fermi-Level ab Initio Molecular Dynamics

Cited by 27 publications

References 71 publications

Reconciling the Experimental and Computational Hydrogen Evolution Activities of Pt(111) through DFT-Based Constrained MD Simulations

Reconciling the Experimental and Computational Hydrogen Evolution Activities of Pt(111) through DFT-Based Constrained MD Simulations

Water dynamics at electrified graphene interfaces: a jump model perspective

Atomic‐Scale Modelling of Electrochemical Interfaces through Constant Fermi Level Molecular Dynamics

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