BREIT INTERACTION EFFECT IN ATOMS

Breit interaction which represent the relativistic correction to the Coulomb repulsion between electrons, have been demonstrated for the average energy of configuration. Breit interaction (magnetic and retardation terms) is treated as a first-order perturbation for all atoms in the periodic table, where the energy shift due to retardation part of the Breit interaction is about 10% of the energy shift due to the magnetic part throughout the periodic table. Also the Breit interaction isintroduce into the self consistent process to calculate the subshells binding energy shift for three selected atoms ( 39 Y , 60 Nd and 90 Th ).