Description of the (2s2)1S, (2s2p)1P, (2p2)1D, and (1snl)1L (n<<6, l<<2) states of the helium atom by the variational method

A new theoretical model and a method of calculation of the wave functions of the autoionization and the (1snl)1Lstates are proposed. The theory is based on the method of superposition of configurations and uses an approximation of basis functions by a linear combination of hydrogen-like functions with effective charges. The resulting wave functions satisfy all the orthogonality requirements. In the approximation ignoring the non-Coulomb part of the He+ potential, the width of the (2s2)1S, (2s2p)1P, and (2p2)1D resonances and the shift of the resonance positions owing to the interaction with the degenerate continuum were calculated. The results of the calculations agree well with the presently available experimental and theoretical data