This confirms the view that electron correlation on the surface of a sphere is qualitatively different from that in three-dimensional physical space.

Electronic exchange is considered, but electron correlation is not.

Neglecting electron correlation can lead to large deviations from experimental results.

Kołos is best known for his work on the theory of electron correlation in molecules.

The correction improves contribution of electron correlation to the energy.

Later, he studied electronic states in disordered systems and electron correlation in narrow band solids.

To account for electron correlation there are many post-Hartree-Fock methods, including:

A number of important theoretical approximations have been proposed to explain electron correlations in these crystalline systems.

This is the case when electron correlation is large.

As a result, the term post-Hartree-Fock method is typically used for methods of approximating the electron correlation of a system.