Abstract
Abstract A multi-configuration (MC)-LCAO-MO method is applied to 1,3-butadiene and cyclobutadiene, predicting their molecular geometries and electronic spectra. The molecular ground state geometry, electronic spectrum and stabilization energy of the trans- to the cis-isomer of 1,3-butadiene are predicted to be in good accord with experiments and with those derived from the ordinary semi-empirical SCF-CI method. The results obtained for cyclobutadiene indicate that (a) the Jahn-Teller distortion occurs to favor a rectangular (D2h) form, the stabilization energy being 0.3–0.9 eV depending on approximations, and (b) even in a square (D4h) form a singlet (ground) state is more stable than a triplet state by ca. 0.3 eV. It is also shown that the lowest excited singlet and triplet states (3A2g and 1B1g) in the square form are not subjected to the Jahn-Teller effect. A discussion is given on a possible error in a CI treatment arising when degenerate molecular orbitals are expressed by real coefficients of atomic orbitals.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.