A molecular dynamics study of the structure of water around the ions Li⁺, Na⁺, K⁺, Ca⁺⁺, Ni⁺⁺ and Cl^-

Abstract

This paper reports a molecular dynamics study of the structure of water around Li⁺, Na⁺, K⁺, Ca⁺⁺, Ni⁺⁺ and Cl^- ions. Jorgensen's TIP4P potential is used for the water-water interaction, and new ab initio SCF potentials have been obtained for Ca⁺⁺/H₂O and Ni⁺⁺/H₂O using the recently developed gradient method. In most cases where experimental results are available the positions of the peaks associated with the coordination shells, the ion-water geometries, and the coordination numbers are in satisfactory agreement. However, we believe that more precise neutron measurements of the coordination number of Ni⁺⁺ in dilute solution are needed. The main effects of high pressure on the structure of water around Cl^- occur in the second coordination shell. High temperature and high pressure are found to have little effect on the structure around Ca⁺⁺.

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Notes on contributors

D.G. Bounds

Ramsay Memorial Fellow 1982–84.