Ab initio bending potential-energy curves for Rydberg states of H 2 O

Using a basis set containing Rydberg s, p and d functions, ab initio configuration interaction calculations have been made for the bending potentialenergy curves of Rydberg states of H2O having excitation energies up to about 12eV. The calculations reveal a large number of avoided crossings between ‘bent’ Rydberg states arising from the excitation of an electron from the 1b1 orbital and ‘linear’ states arising from the excitation of an electron from the 3a1 orbital. Quantum defect functions have been derived from the ab initio results and used to generate bending potential-energy curves for higher Rydberg states.