Efficient linearization of the augmented plane-wave method - art. no. 195134

We present a detailed analysis of the APW+lo basis set for band-structure c alculations. This basis set consists of energy independent augmented plane- wave (APW) functions. The linearization is introduced through local orbital s evaluated at the same linearization energy as the APW functions. It is sh own that results obtained with the APW+lo basis set converge much faster an d often more systematically towards the final value. The APW+lo thereby all ows accurate treatment of systems that were previously unaccessible to line arized APW Furthermore, it is shown that APW+lo converges to the same total energy as LAPW provided the higher angular momenta l are linearized, eithe r by adding extra local orbitals or treating them by LAPW. It is illustrate d that the APW basis functions are much closer to the true form of the eige nfunctions than the LAPW basis functions, This is especially true for basis functions that have a strong energy dependence inside the sphere.