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