As shown in Fig. , other ionization energies are comparable with the reference data except for the first and last second ionization energies. However, it must be pointed out that the calculations are critically dependent on the radii of atoms. Many kinds of radii are estimated using different methods, e.g., van der Waals, empirical, and single covalent radii. They are significantly different. For example, the empirical radius of a hydrogen atom is 25 pm, but van der Waals's radius is 120 pm. This paper employs the radii calculated with selfconsistent-field functions (SCF) . As shown in Tab.2 and Fig. , some positive results are achieved. However, the failures are not negligible. For example, the 11 th ionization energy of Na is 2.7422×10 4 kJ/mol, but the reference value is 159.076×10 4 kJ/mol. It seems that the SCF radius of 190 pm is too big. Similarly, provided that the reference data of ionization energy are correct, the radii of atoms seem too prominent when n>10. Therefore, it is too early to give a relevant conclusion to the calculations of ionization energy.