Atomic Data and Spectral Models for FeII
  We present extensive calculations of radiative transition rates and electron
impact collision strengths for Fe II. The data sets involve 52 levels from the
$3d\,^7$, $3d\,^64s$, and $3d\,^54s^2$ configurations. Computations of
$A$-values are carried out with a combination of state-of-the-art
multiconfiguration approaches, namely the relativistic Hartree--Fock,
Thomas--Fermi--Dirac potential, and Dirac--Fock methods; while the $R$-matrix
plus intermediate coupling frame transformation, Breit--Pauli $R$-matrix and
Dirac $R$-matrix packages are used to obtain collision strengths. We examine
the advantages and shortcomings of each of these methods, and estimate rate
uncertainties from the resulting data dispersion. We proceed to construct
excitation balance spectral models, and compare the predictions from each data
set with observed spectra from various astronomical objects. We are thus able
to establish benchmarks in the spectral modeling of [Fe II] emission in the IR
and optical regions as well as in the UV Fe II absorption spectra. Finally, we
provide diagnostic line ratios and line emissivities for emission spectroscopy
as well as column densities for absorption spectroscopy. All atomic data and
models are available online and through the AtomPy atomic data curation
environment.
