ACCURATE MULTICONFIGURATION HARTREE-FOCK CALCULATIONS OF ISOTOPE SHIFTS IN C-I AND C-IV

A new isotope shift program, part of the MCHF atomic structure package , has recently been written. The program calculates the isotope shift of an atomic level from multiconfiguration Hartree-Fock (MCHF) or conf iguration interaction (CI) wavefunctions and is specially designed to be used with very large CI expansions, for which angular data cannot b e stored on disk. To explore the capacity of the program, large-scale isotope shift calculations have been performed for the 1s(2)2s S-2 and 1s(2)2p P-2 levels in C IV and for the 1s(2)2s(2)2p(2) S-1, 1s(2)2s(2 )2p3s P-1, 1s(2)2s(2)2p(2) P-3 and 1s(2)2s2p(3) S-5 levels in C I. Fro m the isotope shifts of these levels the C-14-C-12 isotope shifts were calculated for the 1s(2)2s S-2-1s(2)2p P-2 transition in C IV and for the 1s(2)2s(2)2p(2) S-1-1s(2)2s(2)2p3s P-1 and 1s(2)2s(2)2p(2) P-3-1s (2)2s2p(3) S-5 transitions in C I. The calculated transition isotope s hifts are in very good agreement with experimental values, available f or the C I transitions. As a check on the overall quality of the wavef unctions, the hyperfine structure interaction constants were calculate d for the levels in C IV.