Coulomb-Breit Interaction

Here frs and (ri-l tM> are, respectively, elements of one-electron Dirac-Fock and antisymmetrized two-electron Coulomb-Breit interaction matrices over Dirac four-component spinors. The effect of the projection operators is now taken over by the normal ordering, denoted by the curly braces in (15), which requires annihilation operators to be moved to the right of creation operators as if all anticommutation relations vanish. The Fermi level is set at the top of the highest occupied positive-energy state, and the negative-energy states are ignored. 

The present calculation takes into account all these effects for Coulomb-Coulomb and Coulomb-Breit interaction and omits effects l)-3) for Breit-Breit interaction. On the other hand we, in contrast to [2], carry out all the calculations in the point nucleus approximation. The corrections to the finite size of nucleus for the bound energy as well as the corrections to the finite size of nucleus for electron interaction are considered separately (see Table 1). 

Coulomb-Breit Interaction in the Case of Two-Electron Configur at ions... 

Coulomb-Breit interaction for two-electron atom is represented by the Feynman diagrams Fig.lc, d, e, f. In this case the corrections to energy are given by... 

Besides taking into account the two-electron diagrams Fig.lc, d, e, f, Coulomb-Breit interaction for three-electron atom represented by the three-electron diagrams Fig.2b, c (as it is mentioned above the contribution of the diagrams Fig.2b, c is considered as doubled contribution of the diagram Fig.2b). The formulas for irreducible part of the diagram Fig.2b is (see the Appendix)... 

The contributions of different diagrams and their separate parts in the case of Coulomb-Breit interaction for configuration (ls1/2)22s1/2 and (lsi/2)22pi/2 are presented in Tables 5 and 6. 

The fully selfconsistent handling of EJ is compared with two perturbative schemes. In the first the Coulomb-Breit interaction is included on the selfconsistent level, while the contributions beyond the Breit interaction (T—B) are added perturbatively. In the second only the Coulomb-interaction is handled selfconsistently. Even for the heaviest atoms the perturbative evaluation of the... 

One further point should be made about the Feynman and Coulomb gauge interactions. It has been shown that the Coulomb-Breit interaction is correct to The... 

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