PNNL

Abstract

The surface potential at the vapor-liquid interface of water is relevant to many areas of chemical physics. We present the first computation of the surface potential of water using ab initio molecular dynamics. We find that the surface potential ? = -18 mV with a maximum interfacial electric field = 8.9 × 107 V/m. A comparison is made between our quantum mechanical results and those from previous molecular simulations. We find that explicit treatment of the electronic density makes a dramatic contribution to the electric properties of the vapor-liquid interface of water. The E-field can alter interfacial reactivity and transport while the surface potential can be used to determine the “chemical” contribution to the real and electrochemical potentials for ionic transport through the vapor-liquid interface. This work was supported by the U.S. Department of Energy’s (DOE) Office of Basic Energy Sciences, Chemical Sciences program and was performed in part using the Molecular Science Computing Facility (MSCF) in the William R. Wiley Environmental Molecular Sciences Laboratory, a DOE national scientific user facility located at the Pacific Northwest National Laboratory (PNNL). Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.