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Udo W. Schmitt And - One of the best experts on this subject based on the ideXlab platform.

  • Multistate Empirical Valence Bond Model for Proton Transport in Water
    The Journal of Physical Chemistry B, 1998
    Co-Authors: Udo W. Schmitt And
    Abstract:

    A multistate empirical valence Bond (MS-EVB) Model for describing proton transport in aqueous systems is presented. In this approach the electrostatic interaction of the solvent water molecules with an exchange charge distribution is explicitly included in the off-diagonal elements of the EVB Hamiltonian. The MS-EVB Model is parametrized to reproduce geometrical and energetic quantities of selected H3O+·(H2O)N clusters. The obtained geometries, formation energies, and energy barriers are in excellent agreement with results from high-level ab initio calculations. It is furthermore applied in a classical molecular dynamics simulation of condensed-phase water with an excess proton in order to estimate the proton-transfer rate.

James R Kirkpatrick - One of the best experts on this subject based on the ideXlab platform.

  • a multistate empirical valence Bond Model for solvation and transport simulations of oh in aqueous solutions
    Physical Chemistry Chemical Physics, 2009
    Co-Authors: Ivan S. Ufimtsev, Andrey G. Kalinichev, Todd J. Martínez, James R Kirkpatrick
    Abstract:

    We describe a new multistate empirical valence Bond (MS-EVB) Model of OH− in aqueous solutions. This Model is based on the recently proposed “charged ring” parameterization for the intermolecular interaction of hydroxyl ion with water [Ufimtsev, et al., Chem. Phys. Lett., 2007, 442, 128] and is suitable for classical molecular simulations of OH− solvation and transport. The Model reproduces the hydration structure of OH−(aq) in good agreement with experimental data and the results of ab initio molecular dynamics simulations. It also accurately captures the major structural, energetic, and dynamic aspects of the proton transfer processes involving OH− (aq). The Model predicts an approximately two-fold increase of the OH− mobility due to proton exchange reactions.

Gerhard Hummer - One of the best experts on this subject based on the ideXlab platform.

  • Proton transport through water-filled carbon nanotubes.
    Physical Review Letters, 2003
    Co-Authors: Christoph Dellago, Mor M. Naor, Gerhard Hummer
    Abstract:

    Proton transfer along 1D chains of water molecules inside carbon nanotubes is studied by simulations. Ab initio molecular dynamics and an empirical valence Bond Model yield similar structures and time scales. The proton mobility along 1D water chains exceeds that in bulk water by a factor of 40, but is reduced if orientational defects are present. Excess protons interact with hydrogen-Bonding defects through long-range electrostatics, resulting in coupled motion of protons and defects.

Martin Čuma - One of the best experts on this subject based on the ideXlab platform.

  • A second generation multistate empirical valence Bond Model for proton transport in aqueous systems
    The Journal of Chemical Physics, 2002
    Co-Authors: Tyler J. F. Day, Alexander V. Soudackov, Martin Čuma, Udo W. Schmitt
    Abstract:

    Building on the previously developed multistate empirical valence Bond Model [U. W. Schmitt and G. A. Voth, J. Chem. Phys 111, 9361 (1999)] for the dynamics and energetics of an excess proton in bulk phase water, a second generation Model is described. This Model is shown to produce similar dynamic and structural properties to the previous Model, while allowing for the use of the full hydronium charge. This characteristic of the Model is required for its implementation in a host of realistic applications beyond bulk water. An improved state selection algorithm is also presented, resulting in a significantly reduced energy drift during microcanonical molecular dynamics simulations. The unusually high self diffusion constant of an excess proton in water due to the proton hopping (Grotthuss) process is observed in the simulation data and is found to be quantitatively in the same range as the experimental value if a quantum correction is taken into consideration. Importantly, a more complete analysis of proto...

  • A Multi-State Empirical Valence Bond Model for Weak Acid Dissociation in Aqueous Solution†
    The Journal of Physical Chemistry A, 2001
    Co-Authors: Martin Čuma, And Udo W. Schmitt
    Abstract:

    The development and application of a multistate empirical valence Bond (MS-EVB) Model for a weak acid dissociation and subsequent proton transport in aqueous solution is described. The weak acid dissociation step is Modeled by the inclusion of an additional EVB state describing the case when proton is bound to the acid's conjugate base. The Model was parametrized for the imidazolium cation deprotonation. Classical molecular dynamics simulation methodology was used to study both equilibrium and dynamic properties of this system. Free energy profiles of the deprotonation reaction, studied using a novel center of excess charge reaction coordinate, reveal the need to include several solvation shells around the weak acid in order to stabilize the hydronium species formed upon the weak acid deprotonation. The solvent atomic density plots examined at selected points along the proton transfer coordinate display a relatively large reorganization of the solvent around the weak acid molecule, caused by the shift in ...

Udo W. Schmitt - One of the best experts on this subject based on the ideXlab platform.

  • A second generation multistate empirical valence Bond Model for proton transport in aqueous systems
    The Journal of Chemical Physics, 2002
    Co-Authors: Tyler J. F. Day, Alexander V. Soudackov, Martin Čuma, Udo W. Schmitt
    Abstract:

    Building on the previously developed multistate empirical valence Bond Model [U. W. Schmitt and G. A. Voth, J. Chem. Phys 111, 9361 (1999)] for the dynamics and energetics of an excess proton in bulk phase water, a second generation Model is described. This Model is shown to produce similar dynamic and structural properties to the previous Model, while allowing for the use of the full hydronium charge. This characteristic of the Model is required for its implementation in a host of realistic applications beyond bulk water. An improved state selection algorithm is also presented, resulting in a significantly reduced energy drift during microcanonical molecular dynamics simulations. The unusually high self diffusion constant of an excess proton in water due to the proton hopping (Grotthuss) process is observed in the simulation data and is found to be quantitatively in the same range as the experimental value if a quantum correction is taken into consideration. Importantly, a more complete analysis of proto...