The original Naval Research Laboratory Tight-Binding(NRL-TB) methodology was designed to only include s, p, and d orbitals inthe basis. Because of this limitation, materials which have f orbitals in their valence bands could not be modeled by the current program. In this work we have expanded the NRL-TB method to account for f orbital interactions and used the modified program to investigate Thorium, Actinium, Lanthanum and Ytterbium, materials whose properties are influenced by f electrons. Using the improved program, we were able to develop a set of Slater-Koster polynomial coefficients for these materials that accurately compute properties such as total energy (fcc, bcc, sc, hcp, and diamond), energy bands, density of states, elastic constants, and phonon frequencies.

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