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

Distance | Energy | |

Calculated | 0.85 Å | -2.68 eV |

Actual | 0.74 Å | -4.75 eV. |

wIth a multiterm wavefunction, we could get good agreement.

Jim Branson 2013-04-22