Interaction energies between H 2O and HX—CH=Y/X=CH—YH for X, Y=CH 2, NH or O — the chemical Hamiltonian approach

Abstract

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 intermolecular interaction energy for the (H 2O) 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 H 2O and the tautomers HX—CH=Y/X=CH—YH (for X, Y=CH 2, 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.