In this note we wish to report our calculations of the spin density distribution in the several hydrocarbon radical anions using the “half-electron” SCF MO [variable beta] method of Dewar1,2. This method calculates the energy of a system in which the unpaired electron is replaced by two “half-electrons” of the opposite spin. In this way one has the pseudo closed-shell system at equilibrium geometry and the resulting energy [E] differs from that [Eo] given by Roothaan's3procedure only for ¼ Jmm