1. The problem statement, all variables and given/known data Consider an ##H_2## molecule where the protons are separated by a wide distance R and both are located on the z-axis. Ignoring the spin degrees of freedom and treating the dipole-dipole interaction as a perturbation, use perturbation theory to estimate an upper limit for the ground state energy of this molecule. 2. Relevant equations 3. The attempt at a solution What I think is that since hydrogen molecule has 0 dipole moment there should be no perturbation to calculate.