Let On be the force constants between planes n and n + 1 such that On = A(1 - cos(nkoa)) (1) na where A and ko are constants while n is any integer (This is common in metals). We also know that W M _ On sin(nKa) (2) n>0 Calculate w and "w by performing the summation over n. Plot w(K ) in the first Brillouin zone for certain a and n. Hint: sin (no) (7 - 0), 050 -2x (3) n n=1