Hydrated Structure and Approximated Complete Hydration Shell of Li~+:A Density Functional Theory Investigation

The density functional theory with Becke's three-parameter exchange potential and Lee-YangParr correlation functional(B3LYP) was used to study the structure of [Li(H2O)n]+(n =1 ～10) hydrated clusters.Our calculations show that four-coordinated structure is more stable than its isomer,fivecoordinated structure,both in gas and aqueous phases.Namely the Li+tends to form four-coordinated conformer in aqueous solution.The Li-O bond distance increases with the increasing water molecules,while the positive charge on Li+decreases.As n 4,the variation of Li-O bond distance and the positive charge on Li+can be neglected.The binding energy of [Li(H2O)n ]+hydrated clusters presents that seven water molecules can form an approximated complete hydration shell of Li+.In addition,IR spectra of [Li(H2O)n ]+hydrated clusters reveals that the O-H stretching vibration are blue-shift with the increasing water molecules,and the absorption bands at ～ 3 600 cm-1and ～ 3 500 cm-1can be attributed to the formation of hydrogen bonds between the second and first hydration shell water molecules,and the third and second hydration shell water molecules.