Make a new copy of ``sch2.C'' called ``kohnsham.C''. Implement the new equations for E and grad in your get_grad_and_E() function in the ``kohnsham.C'' program.
Debugging: Running your newly developed density-functional theory program with f=2 electrons in the 1s state of Hydrogen, verify that it passes the finite-difference gradient test. Note that this depends on your get_grad_and_E() function as well as your exc() and excp() functions. If you fail the finite-difference test, you can isolate the bug by separately turning on and off the Hartree and exchange-correlation terms in both the energy and gradient terms at the same time.