  The detailed atomistic modeling of electrochemically deposited metal
monolayers is challenging due to the complex structure of the metal-solution
interface and the critical effects of surface elec- trification during
electrode polarization. Accurate models of interfacial electrochemical
equilibria are further challenged by the need to include entropic effects to
obtain accurate surface chemical potentials. We present an embedded
quantum-continuum model of the interfacial environment that addresses each of
these challenges and study the underpotential deposition of silver on the gold
(100) surface. We leverage these results to parameterize a cluster expansion of
the electrified in- terface and show through grand canonical Monte Carlo
calculations the crucial need to account for variations in the interfacial
dipole when modeling electrodeposited metals under finite-temperature
electrochemical conditions.
