Nb I-IV and Ag I-IV oscillator strengths

The aim of the present work is to provide new atomic opacity data for two representative 4d elements, niobium (Nb) and silver (Ag), in their first four charge states, namely for Nb I-IV and Ag I-IV. Large-scale calculations based on the pseudo-relativistic Hartree-Fock (HFR) method were performed to obtain the atomic structure and radiative parameters while the expansion formalism was used to estimate the opacities. Wavelengths and oscillator strengths were computed for several million spectral lines in Nb I-IV and Ag I-IV ions.

The reliability of these parameters was estimated by comparison with the few previously published experimental and theoretical results. The newly obtained atomic data were then used to calculate expansion opacities for typical kilonova conditions expected one day after NS merger, a density of {rho}=10^-13^g/cm^3^, and temperatures ranging from T=5000K to T=15000K.