# In the limit of an infinite basis, the Hartree Fock orbital gives the true ground state energy for some systems

The system in question is H$$_{2}$$. Why does the Hartree Fock orbital give true ground state energy for this system?

## 1 Answer

The premisse is not correct. Also for H2 electron correlation is important. As the ground state is a spin singlet, there is no Pauli corration but there still is Coulomb correlation. The ground state therefore contains contributions from multiple Slater determinants even in this relatively simple case.