We investigate the work function (WF) variation of different Au crystallographic surface orientations with carbon atom adsorption. Ab-initio calculations within density-functional theory are performed on carbon deposited (100), (110), and (111) gold surfaces. The WF behavior with carbon coverage for the different surface orientations is explained by the resultant electron charge density distributions. The dynamics of carbon adsorption at sub-to-one-monolayer (ML) coverage depends on the landscape of the potential energy surfaces. At higher ML coverage, because of adsorption saturation, the WF will have weak surface orientation dependence. This systematic study has consequential bearing on studies of electric-field noise emanating from polycrystalline gold ion-trap electrodes that have been largely employed in microfabricated electrodes.
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