Molecular hydrogen adsorption in a nanoporous metal organic framework structure (MOF-74) was studied via van der Waals density-functional calculations. The primary and secondary binding sites for H2 were confirmed. The low-lying rotational and translational energy levels were calculated, based on the orientation and position dependent potential energy surface at the two binding sites. A consistent picture is obtained between the calculated rotational-translational transitions for different H2 loadings and those measured by inelastic neutron scattering exciting the singlet to triplet (para to ortho) transition in H2. The H2 binding energy after zero point energy correction due to the rotational and translational motions is predicted to be ∼100 meV in good agreement with the experimental value of ∼90 meV.
@article{arxiv.0907.0249,
title = {Energetics and dynamics of H$_2$ adsorbed in a nanoporous material at low temperature},
author = {Lingzhu Kong and Guillermo Román-Pérez and José M. Soler and David C. Langreth},
journal= {arXiv preprint arXiv:0907.0249},
year = {2015}
}