While studying about k-points, etc. I came across the terms density of states. What is it's physical meaning. research papers often have DOS graphs in which they segregate s, p, d contributions and talk about fermi level etc. Is this DOS the same as the kohn-sham orbitals that are solved for in standard DFT?.. because actually for many body systems there should be no orbitals and stuff Also, what is the difference between total DOS and projected DOS ?