Density of states of a free electron gas (a) calculate the density of states of a three-dimensional free electron gas dg(e) at zero temperature (b) using a computer program: plot the density of states dg (e) at zero temperature and at finite temperature, i. e. do(e) ffd(e, t) (c) calculate the density of states at the fermi energy, i. e. do(ef) (at t 0 k) (d) calculate the mean value of the energy of the electronic system (at t 0 k) ef 1 e 2dc (e) de (e)t=0k =