The ab initio UHF and multi-reference (MR) UHF natural-orbital (NO) CI methods have been applied to elucidate geometrical structures and electronic energy levels of methylene peroxide which is regarded as a typical example of a quasidegenerate system. The results by MR UHF NO CI are in good agreement with those of the GVB CI method. It is shown that the present CI is closely related to the extended Hartree-Fock CI approach, which is equivalent to the GVB CI or MC SCF CI for diradical species.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry