Pi electron states of the cyclopentadienyl cation: A comparison of complete CI and UHF results

摘要

Complete CI pi electron wavefunctions and energy levels are calculated for the cyclopentadienyl cation and compared to the UHF results of Phillips and Schug J. Chem. Phys.57, 3498 (1972). The projected UHF and CI energies for the lowest singlet (1E2prime;) and triplet (3A2prime;) states are in good agreement, but energies of the projected excited states do not correspond to the lowest CI levels of the same symmetry. In the UHF1E2prime; and3A2prime; wavefunctions, the contribution of excited configurations is smaller than in the CI functions.