The Hartree-Fock approximation is used in solving many-body quantum mechanical systems. The problems of these type of systems are the e-e repulsion term in the Hamiltonian and the single electron wavefunction which is unkown.

I understand that:

1. The e-e repusion term contains two positions variable and is not separable, therefore to solve such problems we need an approximated expression of such term.
2. By using Fock operator, we can determined the single electron wavefunction and solve the problem.

My questions are: how this Fock operator is related with e-e repulsion term and how to proceed from this term to Fock operator? what is the physical interpretation of Fock-operator? Also in particular, which type of systems can be solved from this approximation.