250 & 3.5 & 5 & 0.5\

For each of these abundance subgrids, models with 12 values of effective temperature from 3500 to 5500K and 11 values of logarithmic surface gravities from 0 to 5 were computed (see Figure 2 and Table 5). Models with logarithmic surface gravities lower than 3.5 (giants) were computed in spherical geometry and with a microturbulence parameter of 2 km s$^{-1}$, while the remaining (dwarf) models adopted v$_{\rm t}$ = 1 km s$^{-1}$ and plane-parallel geometry. In the end, 86% of the 23,140 models converged satisfactorily. Convergence was particularly poor for cool dwarfs that are simultaneously $\alpha$ rich and carbon poor.

Details about the atomic and molecular line lists used by the MARCS code are given by @gustafsson02. In a number of instances, they are different from those used by the ATLAS code, as for H$_{2}$O [@barber01], and TiO [@plez03].

Calculation Method
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Similarly to the ATLAS9 ODF calculations, a new metallicity MARCS subgrid is started with the summation of an OS table of atomic line opacities for the relevant abundance mixture and microturbulence parameter. Since line opacity data is needed for many atoms and first ions, it saves time to add the opacities of 