The Tübingen model-atom database TMAD ( http://astro.uni-tuebingen.de/~TMAD) provides ready-to-use model atoms in TMAP format.
TMAD provides, in general, model atoms at maximum size, i.e. using all data from standard atomic-data resources. For model calculations, model ions can be reduced typically to 15 to 20 NLTE levels (Sect. 2.5, cf. Jahn et al. 2007) to avoid unreasonable computation times. In addition, the input for the DB keyword (Sect. 2.5) has to be adjusted to avoid calculations of line profile very far off the line centers where the line absorption is negligible. TMAD uses a standard of 2400 Doppler widths which may be necessary only for models with very high surface gravities.
Models from Sect. 2.4.1 may not include all levels , e.g. for C IV lines in the optical wavelengtzh range around 4660 Å. Thus, a subsequent line-formation calculation with fixed atmospheric structure, i.e. only NLTE occupation numbers for the atomic levels are calculated. It may not be useful to consider all levels given in TMAD. A rule may be to uses five more levels than the highest from which strategic lines are arising.
To calculate the emergent synthetic spectrum, a formal solution is performed with LINE1_PROF. TMAD provides model atoms that account for fine-structure splitting of the atomic levels. These have to be the same line the degenerated levels used for the line-formation calculations. (Sect.2.4.2).