Free energies calculated from radial distribution functions supply information on ultrafast dynamics of solvated ions such as alkali and alkaline earth metal ions hardly accessible by current experimental techniques. Accurate computer simulations can thus be employed as suitable tool for reaction dynamics in the femtosecond and picosecond timescale, and they even allow to clearly distinguish between different ligands in mixed solvates, which is a most difficult task in experiment. (C) 2003 Elsevier B.V. All rights reserved.