Draw energy band diagrams, for k lying between 0 and pi/a (take a=5Ã), for a material whose valence band follows the equation:
Ev= - Ak^2
(E-Ec) = B (k-k1)^2
where k1= 0.2 pi/a
Ec=1.0 eV
A=0.5xB
B=1 eV/[( pi/a)^2]
and calculate the effective masses for conduction and valence bands.