Heitler-London valence bond solution

For example, the (f>i (ri)atomic orbital of the left H atom, whereas the other Is orbital of the right atom is empty, thus H H+. The other icons are self-explanatory. Let us contrast this solution with the valence-bond (VB) solution for H2 which itself rests on the Heitler-London ansatz for the H2 ion. Here one starts from loosely interacting H atoms, which are weakly perturbing each other, such that the atomic orbitals themselves are good approximations for the wave function. In the valence-bond case, the solution for the hydrogen molecule is... 

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