2. (13 points) In class, we have figured out the surface energy of different crystal planes in the FCC crystal using the equation s=2Nbs, where is bond energy, Nb is the number of broken bonds per surface atom, s is the density of surface atoms. - By the same token, figure out the surface energy of different crystal planes of (100),(110), and (111) in the BCC crystal (lattice parameter of a) in the expression of and a. - Compare their surface energy and list them from large to small