Accurate multiconfiguration Hartree-Fock calculations of isotope shifts in C I and C IV

Abstract

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 configuration interaction (CI) wavefunctions and is specially designed to be used with very large CI expansions, for which angular data cannot be stored on disk. To explore the capacity of the program, large-scale isotope shift calculations have been performed for the 1s22s 2S and 1s22p 2P levels in C IV and for the 1s22s22p2 1S, 1s22s22p3s 1p, 1s22s22p2 3P and 1s22s2p3 5S levels in C I. From the isotope shifts of these levels the 14C-12C isotope shifts were calculated for the 1s22s 2S-1s22p 2P transition in C IV and for the 1s22s22p2 1S-1s22s22p3s 1P and 1s22s22p2 3P-1s22s2p3 5S transitions in C I. The calculated transition isotope shifts are in very good agreement with experimental values, available for the C I transitions. As a check on the overall quality of the wavefunctions, the hyperfine structure interaction constants were calculated for the levels in C IV.