PCILO Calculations on Hydrogen Bonded Complexes

The PCILO method was used to study systematically systems with the following types of intermolecular hydrogen bonds: O-H center dot center dot center dot O(sic), O-H center dot center dot center dot O=, N-H center dot center dot center dot O(sic)=, N-H center dot center dot center dot O(sic), NH center dot center dot center dot N(sic), O-H center dot center dot center dot N(sic), N(+)-H center dot center dot center dot O(sic), and N(+)-H center dot center dot center dot N(sic), F-H center dot center dot center dot F-, F-H center dot center dot center dot O(sic), and OH center dot center dot center dot F-. In all cases the KILO method gives a correct description of the stabilization energies in a good agreement with reliable ab initio results. The PCILO calculated equiIibrium distances are only somewhat smaller than the corresponding experimental or ab initio values. Qualitatively, also, the changes in the charge distributions are in accordance with the results of ab initio calculations.