The Pseudopotential Approximation in Electronic Structure Theory

A short review is presented on one of the most successful theories for electronic structure calculations, the pseudopotential approximation, originally introduced by Hans G. A. Hellmann in 1934. Recent developments in relativistic quantum theory allow for the accurate adjustment of pseudopotential parameters to valence spectra, producing results for properties of atoms, molecules, and the solid-state in excellent agreement with more accurate all-electron results if a small-core definition is used. Thus the relativistic pseudopotential approximation is now the most widely applied method for systems containing heavy elements.