  The Generalized Relativistic Effective Core Potential (GRECP) method is
described which allows one to simulate Breit interaction and finite nuclear
models by an economic way and with high accuracy. The corresponding GRECPs for
the uranium, plutonium, eka-mercury (E112), eka-thallium (E113) and eka-lead
(E114) atoms are generated. The accuracy of these GRECPs and of the RECPs of
other groups is estimated in atomic numerical SCF calculations with Coulomb
two-electron interactions and point nucleus as compared to the corresponding
all-electron Hartree-Fock-Dirac-Breit calculations with the Fermi nuclear
charge distribution. Different nuclear models and contributions of the Breit
interaction between different shells are studied employing all-electron
four-component methods.
