================= Density of states ================= Take a look at the :git:`~doc/exercises/dos/dos.py` program and try to get a rough idea of what it can do for you. Use it to plot the density of states (DOS) for the three Fe configurations from the :ref:`iron_exercise` exercise (on the *x*-axis you have the energy relative to the Fermilevel). * Do the DOS plots integrate to the correct numbers? (i.e. number of bands). * The DOS for the anti-ferromagnetic phase looks a bit like that for the non-magnetic phase - is it magnetic at all?! Calculate the magnetization like this: .. literalinclude:: magnetization.py and :ref:`look at it `. * Calculate the DOS for bulk Aluminum and compare it (qualitatively) to the DOS for the non-magnetic calculation. The DOS for a simple metal has this shape: *g*\ (*E*) ~ *E*\ :sup:`1/2`. Explain the qualitative difference. * Plot also the DOS for bulk Si and the CO molecule. Identify the bandgap between valence and conduction bands for Si and the HOMO-LUMO gap for CO. Make sure that your **k**-point mesh for Si is dense enough to sample the band structure. Projected Density of states (PDOS) ---------------------------------- The projected density of states is useful for for analyzing chemical bonding. There exist several studies where the density projected onto the d states of a given surface atom is used. This short exercise demonstrates how to construct the PDOS of Fe. We will get a feel for the local density of states by plotting the PDOS for the ferro-magnetic Fe crystal. Look at :git:`~doc/exercises/dos/pdos.py`. Use it to plot the s, p, and d-states on one of the Fe atoms.