Theoretical investigation of hydrogen bonding interaction in H3O(+)(H2O)9 complex.

Hydrogen bonding interaction of hydronium ion with water molecules in its first and second solvation shell is studied using density functional theory with B3LYP functional and aug-cc-pvtz basis set. The nature of interaction and contribution from various interaction energies to the binding energy of a complex is studied using many-body analysis approach. The hydrogen bonds between hydronium and water molecules in its first solvation shell are stronger than those between water molecules in its second solvation shell. Many-body analysis shows that not only two-body but higher many-body energies up to seven-body interactions are also not negligible whereas eight-, nine-, and ten-body interaction energies are negligible for this complex. The terms containing hydronium ion as one of the many-body components have higher contribution to the respective total many-body interaction energy than those from the terms containing only water molecules. Additive as well as non-additive interactions are attractive and contribute about 58.6 and 44.3% respectively to the binding energy of a complex.