All electron calculations of open‐shell polyatomic molecules. III. Perturbation treatment of the spin polarization in vinyl and methyl radicals

A first order perturbation treatment starting with SCF‐MO'S in canonical or equivalent quasi‐localized form is presented for the hyperfine coupling constants of vinyl and methyl radicals. The spin‐polarisation contribution to hyperfine splittings is found to be large, negative for the proton of the radical center in both radicals and positive for the β protons of vinyl.