S. Goedecker, TREATMENT OF SEMICORE STATES IN THE LINEARIZED AUGMENTED-PLANE-WAVE METHOD AND OTHER LINEARIZED ELECTRONIC-STRUCTURE METHODS, Physical review. B, Condensed matter, 47(15), 1993, pp. 9881-9883
We show that elements with semicore states can be treated by standard
linearized methods if the radius of the muffin-tin sphere is chosen sm
aller than in standard implementations and if appropriate radial basis
functions are used.