The approach of alkali ions towards an electrode surface – A molecular dynamics study

Abstract

The approach of alkali ions from an aqueous solution towards a gold electrode has been studied by biased molecular dynamics. In accord with the Hofmeister series, Li+ and Na+ show signs of structure making, K+ and Cs+ of structure breaking. For all ions the potential of mean force at first rises, when the ion approaches the surface, passes through a maximum and then drops again to a local minimum. For the structure breaking ions Cs+ and K+ the solvation energies in the minima are the same as in the bulk, for Na+ and Li+ they are a little higher.