Published online by Cambridge University Press: 13 February 2013
We discuss the role of Configuration Interaction (CI) and the influence of the number of configurations taken into account in the calculations of nickel and iron spectral opacities provided by the OPAC international collaboration, including statistical approaches (SCO, CASSANDRA, STA), detailed accounting (OPAS, LEDCOP, OP, HULLAC-v9) or hybrid method (SCO-RCG). Opacity calculations are presented for a temperature T of 27.3 eV and a density of 3.4 mg/cm3, conditions relevant for pulsating stellar envelopes.