SIMBAD references

Electron excitation collision strengths (Ω) and transition probabilities (A-values) for the iron-peak element Cr II lines are of high importance for the stellar and nebular abundance studies. Collision and radiative parameters are presented for all possible inelastic transitions between the Cr II 512 fine-structure levels covering infrared to extreme ultraviolet lines. These parameters should allow a detailed modeling and analysis of the available measured stellar and nebular spectra from different astrophysical objects. Accurate target wave functions have been generated using the multiconfiguration Hartree-Fock method together with term-dependent one-electron orbitals and well-chosen configuration expansions. The wave functions are then used in the calculations of transition probabilities and collision rates. The B-spline Breit-Pauli R-matrix method has been employed for the calculation of electron excitation collision strengths. The semiempirical fine-tuning procedure has been applied to the energies of the local supercluster (LS) terms prior to transformation of the Hamiltonian matrices to intermediate coupling. The Hamiltonian matrices for the calculation of collision rates also include spin-orbit interaction. The 512 fine-structure levels of the Cr II 3d⁵, 3d⁴4s, 3d³4s², 3d⁴4p, and 3d³4s4p configurations have been considered in our work. The thermally averaged collision strengths have been determined using a Maxwellian distribution for a wide range of temperatures from 10² to 10⁵ K. The accuracy of our results has been estimated by comparison with other calculated collision rates and available measured radiative rates.