Basis of two unlike atoms. For the problem treated by (18) to (26), find the amplitude ratios u/v for the two branches at K max=π/a. Show that at this value of K the two lattices act as if decoupled: one lattice remains at rest while the other lattice moves. Diatomic chain. Consider the normal modes of a linear chain in which the force constants between nearest-neighbor atoms are alternately C and 10C. Let the masses be equal, and let the nearest-neighbor separation be a/2.Find ω(K) at K=0 and K=π/a. Sketch in the dispersion relation by eye. This problem simulates a crystal of diatomic molecules such as H 2