Structures and Solvation Energies Effects Versus Temperature. An MP2 Investigations in the Framework of Cluster Model

Abstract

ABSTRACT Structures, relative stabilities, solvation enthalpies, and free energies of the cluster in gas and in water phases were investigated in this work using Moller‐Plesset perturbation theory (MP2) and considering a temperature range of 40–400 K. The 12 H2O molecules are distributed between the first, second, and third solvation shells. The calculated distances distances in gas phase are in good agreement with the experimental range which confirms the strong influence of long‐distance interactions in cluster stabilization. Structural comparison between gas and water phases shows that the addition of the bulk solvent causes changes in the cation‐water bond lengths of few hundredths of angstroms. The obtained solvation free energy of beryllium ion in water at room temperature (298.15 K) results in b − 575.1 kcal mol−1 in very good agreement with the corresponding experimental counterpart. The computed solvation free energies increase as a polynomial function of the temperature while the change in the solvation enthalpies is found to be negligible.