BASIS-FREE BAND-STRUCTURE METHOD FOR PERIODIC-SYSTEMS

We develop a basis-free method for calculating the band structures of periodic systems. The many-center problem is divided into one-center p roblems by employing a projection function. The full solution is then obtained by summing over the one-center solutions, ensuring the correc t Bloch symmetry. Due to the division into the one-center problem, the method is expected to scale as similar to N to N-2 where N is the num ber of atoms in the unit cell. Since no basis functions are used the m ethod should be applicable to any system. In particular, systems with low symmetry, such as surfaces or crystals with impurities, should;ben efit from this method.:We demonstrate the feasibility of the method by calculating the free-electron and Cu band structures.