CHARGE-TRANSFER AND CURVE CROSSINGS IN THE [BEH2O]2+ SYSTEM

Diabatic and adiabatic potential energy curves have been determined for the complexation of beryllium cation with a water molecule, by means of multi-reference perturbation CI. The quasi-diabatic states correspond to Be2+H2O and to nine charge transfer states (Be+H2O+): at short beryllium-water distances the ground state is essentially Be2+H2O, but at large distances several charge transfer states have lower energies. The nature of the curve crossings of the ground and lowest excited states in the [BeH2O]2+ system is clarified. The changes brought about by the presence of a second water molecule are investigated.