In searching adequate MO theories for calculation of the sizable system of doublet state, the unrestricted version of MINDO/3 has been examined in various radicals to show that the unrestricted MINDO/3 (UMINDO/3) method has an advantage over the conventional MINDO/3 in that it gives faster geometrical and SCF convergences and more accurate vertical ionization energies for π-conjugate radicals.
