Structure and dynamics of the doubly excited helium atom

The structure and dynamics of the doubly excited metastable states of the helium atom have been investigated. Using wave functions determined by the complex coordinate method, we have calculated the energies, the lifetimes, and the average interparticle distances and the mass polarization energy of the three lowest resonant states of ${}_{}{}^1{}_{}{}^{}$ ${\mathit{S}}^{\mathit{e}}$ symmetry.