Computational physics, local density theory and mixed valence

The role and nature of computational physics and its relationship to the other separate branches of physics - analytic theory and experimental physics - are discussed. Some aspects of local (spin) density functional theory and, in particular, the recent development of an all-electron total energy full potential energy band approach for determining the electronic structure of bulk solids and surfaces (the FLAPW method), are described. An example of the application of this approach is given using results recently obtained for the mixed valent compound, TmSe, by Jansen, Freeman and Monnier.