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Grand canonical electronic density-functional theory: Algorithms and applications to electrochemistry

Cornell Affiliated Author(s)

Author

R. Sundararaman
W.A. Goddard III
Tomas Arias

Abstract

First-principles calculations combining density-functional theory and continuum solvation models enable realistic theoretical modeling and design of electrochemical systems. When a reaction proceeds in such systems, the number of electrons in the portion of the system treated quantum mechanically changes continuously, with a balancing charge appearing in the continuum electrolyte. A grand-canonical ensemble of electrons at a chemical potential set by the electrode potential is therefore the ideal description of such systems that directly mimics the experimental condition. We present two distinct algorithms: a self-consistent field method and a direct variational free energy minimization method using auxiliary Hamiltonians (GC-AuxH), to solve the Kohn-Sham equations of electronic density-functional theory directly in the grand canonical ensemble at fixed potential. Both methods substantially improve performance compared to a sequence of conventional fixed-number calculations targeting the desired potential, with the GC-AuxH method additionally exhibiting reliable and smooth exponential convergence of the grand free energy. Finally, we apply grand-canonical density-functional theory to the under-potential deposition of copper on platinum from chloride-containing electrolytes and show that chloride desorption, not partial copper monolayer formation, is responsible for the second voltammetric peak. © 2017 Author(s).

Date Published

Journal

Journal of Chemical Physics

Volume

146

Issue

11

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015683159&doi=10.1063%2f1.4978411&partnerID=40&md5=4059ab952f57cb31f6b1b66ae429c8ec

DOI

10.1063/1.4978411

Group (Lab)

Tomas Arias Group

Funding Source

DE-SC0004993
DE-AC02-05CH11231
DE-SC0001086

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