https://mazziotti.uchicago.edu/qcdictionary/e_terms/effective_core_potential/index.html Effective core potentials, also known as pseudopotentials, are a way of reducing the computational cost of quantum chemistry calculations and including relativistic corrections for heavy atoms. In this method, the explicit Coulombic interaction of the valence electrons with the nucleus and the core electrons is replaced by a screened pseudopotential. Hugo en-us