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  • Titill er á ensku Theoretical calculations of electrochemical systems
  • Meistara
  • Útdráttur er á ensku

    We present a method of manipulating electrons in a metal slab to simulate an
    electrochemical cell using an applied voltage in planewave DFT calculations. Periodic
    boundary conditions are used to simulate an infinite crystal slab. By setting
    the top and bottom layer of a slab at different potentials, electrons are pushed
    from one side to the other; creating two oppositely charged surfaces. This effect
    depends on the electric field that is produced in the vacuum between periodic
    cells. We compare this method to applying a saw tooth potential, previously
    used by others, and discover that our method gives a better description of the
    electron transfer.
    We also briefly discuss the development of our method to include a potential
    profile similar to the electrical double layer near the metal surface. With our
    method we get the right features of the potential profile when electrons have
    been transferred to the surface, while the sow tooth potential gives exactly the
    opposite direction of the potential profile with regards to the electron transfer.
    We believe this could be a useful method when calculating adsorption energies of
    different species as a function of bias.
    We also discuss the usage of a potential energy surface based on the single center
    multipole expansion in a QM/MM context with DFT calculations. This opens
    the possibility of using DFT calculations for the active region at the interface,
    while the bulk water phase is described with the less computationally demanding
    potential energy surface.

  • 9.3.2011

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