Correlation energy of intrashell doubly excited states of heliumlike atoms

The analysis of correlation energy of the simplest first approximation of a variational method for the intrashell states of two-electron atoms is the purpose of the present work. This method allows to divide energy of atom on Coulomb and additional not - Coulomb correlation parts with very high accuracy. Thus all the Coulomb interaction completely is taken into account in calculation and not-Coulomb terms enter only in additional correlation energy. The general formula for energy of additional correlation interaction is obtained and the constant of this interaction is determined. The algorithm of calculation of total energy of two-electron atoms is offered. The outcomes of calculations for intra-shell states are adduced and compared to the experimental data . The arguments for the capability of existence of the analytical solution for a three-body problem in atomic physics are presented. Some reasons about probable practical consequences are presented. Most interesting of them is the discovery that under certain conditions additional electron-electron attraction can exceed classical electron-electron repulsion.