Molecular hydrogen interaction with IRMOF-1: A multiscale theoretical study

By means of ab initio quantum chemical techniques, the interaction of molecular hydrogen with the first member of the IRMOF family is explored. Many different models and computational schemes, ranging from second-order Moller-Plesset perturbation theory (MP2) to density functional theory (DFT), have been applied in order to find the best model that can describe the IRMOF-1 cell in an accurate manner against moderate cornputational cost. The results show that the interaction energies of dihydrogen with the inorganic part of the tRMOF-1 are between 0.13 and 0.74 kcal/mol and can be attributed to dipole-induced dipole forces. Basis-set superposition errors are corrected for by the function counterpoise method. The effect of the corrections is large, almost 50% of the uncorrected interaction energy. Furthermore, the correction may shift the minimum of the potential energy curve toward larger distances. The computational approaches used in this study, allow us to find the true minimum of the potential hypersurface. As a conclusion, both organic and inorganic linkers contribute equally to dihydrogen physisorption.