Based on the B-spline basis method, the properties of the helium atom confined inside an endohedral environment,such as buckminster fullerene, are studied. In our calculations, the endohedral environment is a parabolic potential well. In this situation, the phenomenon of 'mirror collapse' is exhibited for energy levels of a confined helium atom. The 'giant resonance' of oscillator strength of the dipole transition emerges with the variation of depth of the confining well. The physical mechanisms of these phenomena are analyzed in this paper.
A semi-empirical atomic structure model method is developed in the framework of a relativistic case. This method starts from Dirac-Fock calculations using B-spline basis set. The core-valence electron correction is then treated in a semiempirical core polarization potential. As an application, the polarization properties of alkali metal atoms, including the static polarizabilities and long-range two-body dispersion coefficients, have been calculated. Our results are in good agreement with the results obtained from ab initio relativistic many-body perturbation method and the available experimental measurements.
