harmonic3dhfb

0) Need to define different nshell for x,y,z.

1) Need to compute potentials after Hamiltonian, density step, but before compute observables.

2) Need to compute divJ density.

3) Need to compute Coulomb potential more accurately.

5) Need to remove analytic derivatives in Hamiltonian for kinetic term, for ones using derivatives functions so we can handle a effective mass. Also important since quadrature points are only accurate for derivative functions.

6) Need exit condition after computing observables.

7) Need to include linear mixing of potentials after computing observables.

8) Need to place all functions in a for loop.

9) Need to speed up functions.

...) Eventually odd terms, other functionals, constraints, restart feature, writing of wfs/densities, and potential energy surface feature.