Addressing electrified metal-electrolyte interfaces with Non-Equilibrium Green's Functions*

We demonstrate how Non-Equillibrium Green's Functions techniques can be used to address, from first principles, the atomistic description of metal-electrolyte interfaces in the presence of an external bias applied to the electrodes. The NEGF method allows to deal with open, non-periodic systems driven out of equillibrium by the external applied bias. We use the TranSIESTA method and code [1,2], developed within the SIESTA project [3]) to study problems involving steady-state non-equilibrium situations in nanoscale costrictions, where an external electric bias is applied between the two sides of the constriction, establishing a steady electric current. We show how this computational machinery can be also used to study electrified solid/liquid interfaces [4], where an external bias is applied to the solid electrode. Here, one is not concerned with the quantum electronic transport, but with the effect of the external bias on the structural changes, dynamics and chemical reactions induced at the metal/liquid interface. I will show molecular dynamic simulations of aqueous electrolytes as a proof of concept for future realistic, atomistic first-principles simulations of electrochemical processes.

References:
[1] M. Brandbyge, J.L. Mozos, P. Ordejón, J. Taylor, and K. Stokbro, Phys. Rev. B 65, 165401 (2002).
[2] N. Papior, N. Lorente, T. Frederiksen, A. García, M. Brandbyge, Computer Physics Communications 212, 8 (2017).
[3] J.M. Soler, E. Artacho, J.D. Gale, A. García, J. Junquera, P. Ordejón, D. Sánchez-Portal, J. Phys.: Condens. Matter., 14, 2745 (2002).
[4] L.S. Pedroza, P. Brandimarte, A.R. Rocha, M.V. Fernandez-Serra, Chem. Sci., 62, 9 (2018).