Configuration interaction calculations on o3 and o-3

In a theoretical study to choose between the several experimental values for the vertical electron affinity of O3, configuration interaction calculations were performed for O3 and O-3. Large Gaussian basis sets and symmetry adapted complex functions were used. To a good approximation, the electron affinity for O3 should be equivalent to the difference in the calculated single excitation ci results for O3 and O-3. The difference between natural orbital single excitation ci results for O3 and O-3 gave a vertical electron affinity of 2.12 eV. This calculated value is in excellent agreement with the recent experimental photodetachment measurements of Beaty, 2.1-2.2 eV. This agreement implied that the equilibrium geometry of O-3 was similar to that of O3. ci calculations of the potential curves of O3 and O-3 from 114.8d̀ to 118.8d̀ indicate that the equilibrium geometry of the ion is close to that of the parent molecule. Higher excitation CI calculations were carried out using iterative natural orbitals resulting from lower excitation CI calculations.