Theoretical studies of Li(H2O)19+, Li(H2O)20+ and Li(H2O)21+ clusters

Li(H2O)19-21+ clusters with broken and distorted dodecahedral cages (metal in cavity) are studied by optimizing geometry at the B3LYP/6-311++G** level. The stabilization energy per monomer (SEP) for the Li(H2O)19+ cluster (15.2 kcal/mol) is almost the same as that for the Li(H2O)20+ cluster (15.1 kcal/mol) with a relatively large drop in the SEP value to 14.8 kcal/mol for the Li(H2O)21+ cluster. While Li in Li(H2O)20+ is negatively charged, it is neutral in Li(H2O)19+, and may favor the formation of Li(H2O)20+ over Li(H2O)19+ and hence, a magic peak in mass spectrum is expected at Li(H2O)20+.