Hydration Free Energies of Molecular Ions from Theory and Simulation

We
present a theoretical/computational framework for accurate calculation
of hydration free energies of ionized molecular species. The method
is based on a molecular theory, 3D-RISM, combined with a recently
developed pressure correction (PC+). The 3D-RISM/PC+ model can provide
∼3 kcal/mol hydration free energy accuracy for a large variety
of ionic compounds, provided that the Galvani potential of water is
taken into account. The results are compared with direct atomistic
simulations. Several methodological aspects of hydration free energy
calculations for charged species are discussed.