molecule consists of four particles bound together:
, and proton
The Hamiltonian can be written in terms of the
the repulsion between electrons,
plus a correction term for double counting the repulsion between protons.
We wish to compute variational upper bound on
and the energy.
We will again use symmetric electron wavefunctions,
where the spin singlet is required because the spatial wfn is symmetric under interchange.
The space symmetric state will be the ground state as before.
From this point, we can do the calculation to obtain
|| 0.85 Å
|| -2.68 eV
|| 0.74 Å
|| -4.75 eV.
wIth a multiterm wavefunction, we could get good agreement.