Figure 2.

(a) Mg²⁺−H₂O dimer energy vs Mg−O distance computed with different empirical force-fields as described in text and compared with ab initio calculation using MP2 method with the 6-311+ +G(3d,3p) basis set (shown as a black line) The line colors are the same as in Figure 1d. (b) Energy of the Mg²⁺−(H₂O)₆ cluster vs Mg− O distance for pulling of one of the ligands out of the equilibrium cluster (see the description of the calculation set up in text). Colors are the same as in Figure 1d.