lculations. Similarly, the uncertainty on the calibration of $\alpha_\mathrm{MS}$ essentially comes from the spread of the MS in the CMD. The effects of the indetermination on age and $\alpha_\mathrm{MS}$ on surface $^7$Li abundance are evaluated for each cluster and quadratically added to the other error sources to define the theoretical surface lithium abundance error bars. Table \[tab:oc\_cmd\] summarizes the results for the main parameters of each cluster, namely, chemical composition, $\alpha_{\mathrm{MS}}$, and age. For Ngc 2516 two different \[Fe/H\] values are available: (1) \[Fe/H\] = $-0.10$ (photometric) and (2) \[Fe/H\] = $+0.07$ (spectroscopic). Since the spectroscopic value is still quite uncertain, because it has been determined using only two stars [see the discussion in @terndrup02], we decided to also use the photometric one for the following comparison with surface lithium data.

The age determination for the selected clusters was performed both with models without core overshooting ($\lambda_\mathrm{ov} = 0$) and with a standard upper limit for the presence of overshooting, $\lambda_\mathrm{ov} = 0.2$ [see e.g., @brocato03; @claret07 and references therein], in order to take a suitable range of $\lambda_\mathrm{ov}$ into account. However, as shown in Table \[tab:oc\_cmd\], the age difference is for all the cases close to the quoted uncertainty. Moreover, the impact of the age uncertainty on $\epsilon_\mathrm{Li}-T_\mathrm{eff}$ profile is almost negligible for clusters older than about 80 - 90 Myr, since all the stars have already reached the ZAMS, so that their position in the CMD is weakly dependent on the age. The situation is different for very young clusters, such as Ic2602 and $\alpha$ Per. In this case low-mass stars are close but not yet in ZAMS, so an age variation produces an appreciable change in $T_\mathrm{eff}$.

As for the age, the $\alpha_\mathrm{MS}$ uncertainty also has a small effect on the predictions of surface $^7$Li, since in the age and mass range we are investigating, 