Most adsorption energies follow a trend were the adsorption energies increases as the metal moves downwards in group 13. Adsorption on AlN has the lowest standard energy of adsorbate formation, indicating that adsorption onto AlN is most preferred. On GaN, the energies are slightly higher by around 70 kJ/mol, compared to AlN. Continuing to InN, the adsorption energies are even higher than on GaN by around 50 kJ/mol, showing that adsorption on InN is least favorable. Adsorption of hydrogen deviates from the trend. The difference in adsorption energy of hydrogen between AlN and GaN is negligible, but the energy is much higher for InN.