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The multiconfiguration Dirac-Fock method allows to calculate the state ofrelativistic electrons in atoms or molecules. This method has been known for along time to provide certain wrong predictions in the nonrelativistic limit. Westudy in full mathematical details the nonlinear model obtained in thenonrelativistic limit for Be-like atoms. We show that the method with sp+pdconfigurations in the J=1 sector leads to a symmetry breaking phenomenon in thesense that the ground state is never an eigenvector of L^2 or S^2. We therebycomplement and clarify some previous studies.

Symmetry Breaking of Relativistic Multiconfiguration Methods in the Nonrelativistic Limit