The electronic structures of biradicals in the unrestricted Hartree-Fock approximation

Abstract The electronic structures of biradicals are investigated by the unrestricted Hartree-Fock (UHF) method and explained in terms of spin density wave (SDW) orbitals. The biradical characters are calculated by the use of the occupation numbers of the natural orbitals in the SDW configuration. The results are wholly compatible with those of other methods of calculation.