The presence of Fe 2+ on interstellar silicate surfaces renders them good reservoirs of H atoms that are ready to recombine to form H 2.
Using periodic DFT-D2 methods, atomistic simulations of interstellar H adsorption and H 2 formation on a (010) Fe-containing olivine surface are presented. At variance with the (010) Mg 2SiO 4 surface and key to these processes are the large Fe/H interaction energies, suggesting that olivine surfaces are good reservoirs of H atoms for subsequent recombination to form H 2.