Hartree theory

Ignoring the exchange-correlation terms represents the first mean-field many-electron theory, ``Hartree theory.'' We will begin with this theory as it involves energy terms with which we are already familiar.

Add all terms to getE() and H() from Eqs. (18,20) which involve $\phi$.
Hints: Note that you will have to build the density n and solve Poisson's both in get() and in H(). Don't forget to orthonormalize the wave functions before computing n!