Pseudopotentials and modelpotentials

The basic assumptions of quantum chemical ab initio valence‐only (VO) schemes, i.e., pseudopotential and modelpotential approaches, are briefly discussed. Both effective core potential schemes lead to a reduction of the computational effort for wavefunction‐based as well as density functional theory electronic structure calculations in comparison to corresponding all‐electron treatments and allow to include the most important relativistic contributions implicitly into formally nonrelativistic calculations by means of a suitable parameterization of the VO model Hamiltonian.