PNNL

Abstract

We have resolved the apparent inconsistency in quantifying the electrochemical surface potential at the liquid-vapor interface when using explicit ab initio electronic charge density and effective atomic partial charge models of liquid water. It is shown that regions of space must be excluded for the evaluation of the electric potential from a charge distribution to be useful in the interpretation of electrochemical measurements. This is not the case for work functions, electron diffraction or electron holography measurements. We find that the resulting electric potentials from partial charge models and ab initio charge distributions are quite different except for those regions of space between the molecules where the electron density is nearly zero. We compare our computed ab initio surface potential with high-energy electron diffraction and holography measurements and find good agreement. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.