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Understanding the Fe II emission from Active Galactic Nuclei (AGN) has been agrand challenge for many decades. The rewards from understanding the AGNspectra would be immense, involving both quasar classification schemes such as"Eigenvector 1" and tracing the chemical evolution of the cosmos. Recently,three large Fe II atomic datasets with radiative and electron collisional rateshave become available. We have incorporated these into the spectral synthesiscode Cloudy and examine predictions using a new generation of AGN SpectralEnergy Distribution (SED), which indicates that the UV emission can be quitedifferent depending on the dataset utilized. The Smyth et al dataset betterreproduces the observed Fe II template of the I ZW 1 Seyfert galaxy in the UVand optical regions, and we adopt these data. We consider both thermal andmicroturbulent clouds and show that a microturbulence of $\approx$ 100 km/sreproduces the observed shape and strength of the so-called Fe II "UV bump".Comparing our predictions with the observed Fe II template, we derive a typicalcloud density of $10^{11}$ cm$^{-3}$ and photon flux of $10^{20}$ cm$^{-2}$s$^{-1}$, and show that these largely reproduce the observed Fe II emission inthe UV and optical. We calculate the $I$(Fe II)/$I$(Mg II) emission-lineintensity ratio using our best-fitting model and obtain log($I$(Fe II)/$I$(MgII)) $\sim$ 0.7, suggesting many AGNs have a roughly solar Fe/Mg abundanceratio. Finally, we vary the Eddington ratio and SED shape as a step inunderstanding the Eigenvector 1 correlation.

Improved Fe II emission line models for AGN using new atomic datasets