Many-body calculations of spectroscopic properties of the 3s3p³P and 3s3d³D states in Mg

Many-body perturbation theory within the algebraic approximation has been applied to compute properties of the double open-shell states 3s3p 3 P and 3s3d 3 D in Mg. The computed results are based on a complete perturbation expansion to third order, and even a few fourth-order core polarisation diagrams have been considered. The properties considered are the specific mass shift and field shift contributions to the 26 Mg- 24 Mg isotope shifts in the transitions 3s 2 1 S-3s3p 3 P and 3s3p 3 P-3s3d 3 D, the fine structure and isotope shift in the fine structure of the 3s3p 3 P state, and finally the magnetic hyperfine structure of the 3s3p 3 P state. Good or reasonable agreement with experiments was obtained in all cases, except for the isotope shift in the fine structure where only a qualitative agreement was obtained.