Quantum mechanical calculation of thermodynamic functions of solvation of ammonium ions in water

The application of an extended version of the generalized Born formula including dielectric saturation effects, implemented within the SCF-CNDO/2 approximation, provides a complete set of data concerning the thermodynamics of solvation of some ammonium ions in water. The calculated free energies of solvation are in good agreement with experimental data. An estimation of the entropy and enthalpy of solvation is also given and satisfactory qualitative trends are obtained.