Here we've made things simpler by choosing a smaller Fermi energy, 1.36 eV. Except for minor distortion of the shape of the "Fermi circle" the picture is the same as in "sommerfeld". With run, the electric field drives the distribution to the left to the steady state value of roughly e*E*tau/h-bar. For these electrons at low energies, the velocity is approximately v = h-bar*k/m and the Sommerfeld picture is fully recovered. A different curvature at the bottom of the band could be easily included by changing m to m*.