Induced Dipole Interactions in the Primary Solvation Sheath

Ion-Induced Dipole Interactions in the Primary Solvation Sheath 

At this level of sophistication, one wonders whether there are other subtle 

For instance, when the water molecule is in contact with the ion, the field of the latter tends to distort the charge distribution in the water molecule. Thus, if the ion is positive, the negative charge in the water molecule tends to come closer to the ion, and the positive charge to move away. This implies that the ion tends to induce an extra dipole moment in the water molecule over and above its permanent dipole moment. For small fields, one can assume that the induced dipole moment is proportional to the inducing field X 

one must consider the contribution to the heat of formation of the primary solvated ion (i.e., step 3 of the cycle used in the theoretical calculation presmted earlier), which arises from interactions between the ion and the dipoles induced in the water molecules of the primary solvent sheath. The interaction energy between a dipole and an infinitesimal charge dq is -p dq/P, or, since dq/P is the field dX due to this charge, the interaction energy can be expressed as -p dX. Thus, the interaction energy between the dipole and an ion of charge ZjCo. exerting a field zf /P, can be found by. 

Considering a mole of ions and four water molecules in contact with an ion, the heat of ion-induced dipole interactions is 

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