INTERACTION ENERGIES BETWEEN H2O AND HX-CH=Y/X=CH-YH FOR X, Y=CH2, NH OR O - THE CHEMICAL HAMILTONIAN APPROACH

Ab initio calculations are performed to investigate systematically the applicability of a newly developed chemical Hamiltonian approach to the calculation of intermolecular interaction energies. The basis-set-superposition-error contribution to the inter-molecular interaction energy for the (H2O)2 dimer is evaluated by using the Boys-Bernardi scheme and the chemical Hamiltonian approach with conventional energy, using various basis sets. The interaction energies between H2O and the tautomers HX-CH = Y/X = CH-YH (for X, Y = CH2, NH or O) are calculated. The results show that the chemical Hamiltonian approach is an excellent method for correcting the basis-set-superposition error in interacting systems, giving reliable results even for moderate basis sets.