In this work we utilized two separate models for citrate anions and sodium counter-ions. One set of sodium citrate interactions used charges and Lennard-Jones parameters from Chong et al. The central backbone of the citrates were kept rigid by fixing the bond lengths between the hydroxyl oxygen -hydroxyl hydrogen (0.945 Å), central carbon -hydroxyl oxygen (1.41 Å), and central carbon -central carboxylate carbon (1.529 Å). These constraints prevent unphysical intramolecular hydrogen bonding between the hydrogen and central carboxylate oxygens, which has been previously observed in this and other related citrate models. To study the effect of these con-straints, we also simulated planar interfaces using all-atom sodium citrate interaction parameters from Wright et al. which include all hydrogen atoms and do not require any internal constraints. For all systems studied, rigid body SPC/E water molecules were used as solvent. For interactions between gold atoms and SPC/E water atoms, we utilize a Mie potential with a functional form taken from Dou et al. and subsequently modified to facilitate citrate binding. Further details are available in the SI.