Q.23: Given the tight binding dispersion relation ( E(k)=E_{0}+A sin ^{2}left(rac{k a}{2} ight) ), where ( E_{0} ) and ( A ) are constants and a is lattice parameter. Calculate the group velocity of an electron? (Hint: Group velocity is given by ( V_{g}=rac{1}{hbar} rac{partial E}{partial k} ) ).

Q.23: Given the tight binding dispersion relation B(k)=E0+Asin2(2kg), where Eo and A are constants and a is Iatice purameter, Calculate the group velocity of an electron? (Hint: Group velocity is given by Vg=h1JNak )