用X_a方法,不论是非相对论性或相对论性方法,多重散射波法或离散变分法,计算的电离能与实验值符合还比较好,但是4f壳层电子集居数偏离整数较远,经验证这不是由于选择基组或集居数分析方法不当造成的,这与光学和磁学的实验结果不一致,它也意味着4f轨道参与成键的作用相当大,与化学实验事实不符,本文分析产生这一问题的原因并提出一种比较简单的处理方法,得出较好的结果。 Using the X_a method, the calculated ionization energies are in good agreement with the experimental values, either by non-relativistic or relativistic methods, by multiple scattering methods or by discrete variational methods. However, the 4f shell electrons are far away from the integers, This is not due to improper choice of basis set or population analysis method, which is inconsistent with the experimental results of optics and magnetism. It also means that the role of 4f orbitals involved in the formation of bonds is quite large and inconsistent with the fact of chemical experiments. The reason for this problem and put forward a relatively simple approach to obtain better results.