The nonadditive effects in the mixed trimers composed of the water dimer and diatomics H 2, HF, HCl, HBr, and ClF

Abstract

Optimal structures, interaction energies and harmonic vibrational frequencies of the (H 2O) 2⋯HX, HX=H 2, HF, HCl, HBr, and (H 2O) 2⋯CIF ternary complexes have been determined from the supermolecular MP4 and CCSD(T) calculations with the aug-cc-pVDZ and the aug-cc-pVTZ basis sets. We located three low-energy configurations on the potential energy surface corresponding to H-bonded cyclic complexes and one linear structure in the case of (H 2O) 2⋯CIF and (H 2O) 2⋯H 2. The tunneling motion of the water molecule across the plane of the heavy atom ring was studied. The contribution of the three-body term represents as much as 24% for (H 2O) 2⋯HBr and the smallest value of 5% for (H 2O) 2⋯H 2 of the total CCSD(T) interaction energy. The nonadditivity originates mainly from the induction effect.