in metallicities give altogether 1980 different compositions for the ATLAS9 models and 175 compositions for the MARCS models. The number of acceptable models may vary for each composition, for details see the ATLAS-APOGEE website (http://www.iac.es/proyecto/ATLAS-APOGEE/). For missing metal-rich compositions of ATLAS9 models see Table 2.](figure01.eps){width="2.5in"}

ATLAS9 Model Atmospheres
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Parameters
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The metallicity (\[M/H\]) of the grid varies from $-$5 to 1.5 to cover the full range of chemical compositions and scaled to solar abundances[^4]. For each of these solar scaled compositions we also vary the \[C/M\] and \[$\alpha$/M\] abundances from $-$1.5 to 1 (Figure 1).

ODFs and Rosseland opacity files were calculated with microturbulent velocities v$_{\rm t}$ = 0, 1, 2, 4, 8 km s$^{-1}$, while the model atmospheres were produced only with v$_{\rm t}$ = 2 km s$^{-1}$. The metallicity grids were the same for all effective temperatures, and the range can be seen in Table 1. Some metal-rich compositions with high C but low $\alpha$ content were not calculated due to excessive computation time; these are listed in Table 2. The $\alpha$ elements considered when varying \[$\alpha$/M\] were the following: O, Ne, Mg, Si, S, Ca, and Ti. The temperature and gravity parameter grid for each composition 