Partitioning of the Electron Correlation Energy

Electron-electron correlation forms the basis of difficulties encountered in many-body problems. Accurate treatment of the correlation problem is likely to unravel some nice physical properties of matter embedded in this correlation. In an effort to tackle this many-body problem, an exact partition function for the correlation energy between two interacting states is proposed in this study. Using this partition function, a model potential for a two-electron system is derived. The model potential can accurately reproduce the singlet states of a singly excited neutral helium atom with one of its electrons frozen in the $1s$ orbital.