Comparison of cross sections for the process Na(3s) + H  →  Na(3p) + H. The dotted line shows the Drawin cross section and the dashed line the Landau-Zener cross section. The full lines are two quantum scattering calculations using different input quantum-chemical data (MRDCI, which is largest near the threshold, and pseudopotential; see Belyaev et al. 2010, for details). The circles show the experimental data of Fleck et al. (1991); Belyaev et al. (1999) with 1σ error bars.