The Hamiltonian of sodium atom is reduced by using screening Coulomb potential, and the energy levels of sodium atom are calculated by means of twofold perturbation.
用屏蔽库仑势简化了钠原子的哈密顿，用两次微扰法计算了钠原子的能量，结果与实验值符合得较好。
2
The equation of motion of two-electron atom in 3-D space is transformed into that of one-electron atom in 6-D space, subjected to generalized Coulombic potential.