In the tight binding model, the energy is given by E(k) = E0 – a – g S e ik(tm-tj) where m and j refer to nearest neighbors. (a) Show that for a bcc structure, the k-dependence of the energy is given by: -8g (cos kxa/2) (cos kya/2) (cos kza/2). (b) Find a similar expression for the k-dependence of the energy for a fcc structure. (c) For small k, determine the effective mass for both structures. (d) At which points in k-space are the minimum and maximum energy values