Core-valence electron correlation effects in photodetachment of Ca- ions -art. no. 012704

The R-matrix method has been used to perform a five-state (S-1-P-2(o)-D-3-D -1-P-1(o)) close-coupling calculation on the photodetachment of Ca- ions wi th photon energies from threshold to 4 eV. Calculations both with and witho ut the core-valence electron correlation are carried out. The dominant core -valence electron correlation is included by exciting one 3p electron to th e valence orbitals. It has been found that the so-called core-valence corre lation is quite crucial to the prediction of the position of the Cooper min imum and the distinct behavior of the photodetachment cross sections near P -3(o) and P-1(o) thresholds. The core-valence correlated calculation result s in a Cooper minimum at 1.20 eV and a narrow shape resonance just above th e 4s3p P-1(o) threshold. These structures are in good agreement with experi mental observations. The present result also supports the previous conclusi on that core-valence electron correlation is responsible for reducing the e lectron affinity of valence-only results to much closer to the experiment.