(631g) Multiscale Modeling of the Electrode/Electrolyte Interface Using Charge Optimized Many Body (COMB3) Potentials

MULTISCALE MODELING OF THE
ELECTRODE/ELECTROLYTE INTERFACE USING MODIFIED CHARGE OPTIMIZED MANY BODY (ECOMB3)
POTENTIALS

Sneha A. Akhade¹*, Andrew Antony²,
Tao Liang², Michael J. Janik¹, Janna M. Maranas¹
and Susan B. Sinnott²

¹Department of Chemical Engineering,
Fenske Laboratory, Pennsylvania State University, State College, PA 16802

²Department of Materials Science
& Engineering, 549 Gale Lemerand Drive, Gainesville, FL 32611, University
of Florida

*Email: saa243@psu.edu

Present day advances in computer simulation have
greatly accelerated material discovery and the investigation of bulk and
surface properties that are relevant to the reactivity and performance of the
material. Electrocatalytic systems present unique challenges to atomistic and electronic
structure modeling due to the presence of an electrode/electrolyte interface
and the integration of electrical currents and chemical reactions.

Our
objective is to develop robust methods that can provide a reasonable atomistic
description of the electrode/electrolyte interface that can be used to
investigate the complex underlying interfacial chemistry. We combine Density
Functional Theory (DFT) and a force field (FF) based classical approach to
construct an atomistic modeling tool to consider this interface. Two key
features of the electrochemical interface are incorporated - metal
polarizability and the interfacial electrolyte chemistry in the presence of a
potential-controlled field. In our previous study [1], we employ a reactive
modified central force-field (mCF) model that uses simple point charges with
pairwise interactions to model reactive water that can dissociate under the
influence of potential controlled metal electrode. The electrodes are held at
constant potential by using a charge fluctuation approach called Electrode
Charge Dynamics (ECD) [2]. However the mCF model assigns a fixed
charge/oxidation state to the water species and the ECD scheme does not permit
charge exchange between the electrode and the electrolyte. In this work, we report
third-generation Charge Optimized Many Body potentials (COMB3) [3] in
conjunction with an electrode charge equilibration scheme (ECOMB3) for modeling
the electrified interface.  This reactive FF model advantageously allows for a
multi-body charge equilibration within a constant potential controlled
environment. Our results compare and test the efficacy of the two models using molecular-scale
tools that are developed to probe the electrochemical and interfacial
properties and provide a reliable atomistic description of the complex
electrode/electrolyte interface.

1.         Yeh, K.-Y., M.J. Janik, and J.K. Maranas, Molecular dynamics
simulations of an electrified water/Pt(111) interface using point charge
dissociative water. Electrochimica Acta, 2013. 101(0): p. 308-325.

2.         Guymon, C., et al., Simulating an
electrochemical interface using charge dynamics. Condens. Matter Phys,
2005. 8: p. 335-356.

3.         Liang, T., et al., Classical atomistic
simulations of surfaces and heterogeneous interfaces with the charge-optimized
many body (COMB) potentials. Materials Science and Engineering: R: Reports,
2013. 74(9): p. 255-279