Electronic structure, statistical mechanical simulations, and EXAFS spectroscopy of aqueous potassium

We investigate the solvation structure of aqueous potassium ions, using a combination of electronic structure calculations, statistical mechanical simulations with a derived polarizable empirical potential and experimental measurement of the extended X-ray absorption fine structure (EXAFS) spectra. The potassium K-edge (at 3,608 eV) EXAFS spectra were acquired on the bending magnet of sector 20 at the Advanced Photon Source, at ambient conditions and for the concentrations of 1 and 4 m KCl. We focus on the coordination distances and the degree of disorder of the first hydration shell as determined by electronic structure calculations, molecular dynamics simulations and experimental measurement. Finally, we characterize the changes of the structure in the first hydration shell with increasing temperature as predicted by molecular simulation