RELATIVISTIC MODIFICATION OF ASYMPTOTIC CONFIGURATION-INTERACTION IN THE CARBON ISOELECTRONIC SEQUENCE

Relativistic configuration interaction and many-body perturbation calc ulations have been performed on the J = 0 ground state of the carbon i soelectronic sequence up to Z = 106 (Z is nuclear charge) to establish quantitatively the way relativity alters the asymptotic configuration interaction. Although it is inappropriate to use relativistic many-bo dy perturbation theory (RMBPT) based on a single-configuration referen ce state (1s(2)2s(2)2p(1/2)(2) J = 0) for low-Z members of the isoelec tronic sequence due to strong mixing among several configuration state s (i.e, quasi-degeneracy), the results of relativistic configuration i nteraction and many-body perturbation calculations demonstrate that RM BPT can be applied successfully to high-Z members in which strong mixi ng almost vanishes.