Ab initio studies of hydrogen-bonded complexes: The H2O dimer, trimer and H2OCO

The interaction energy of (H2O)2, (H2O)3 and H2OCO complex calculated using ab initio methods combined with supermolecular approach are −4.88, −13.85 and −1.68 kcal/mol, respectively, while using the multipolar expansion method they are −4.667, −13.858 and −1.714 kcal/mol, respectively.