Energetics and dynamics of H(2) adsorbed in a nanoporous material at low temperature.
Molecular hydrogen adsorption in a nanoporous metal-organic framework structure (MOF-74) is studied via van der Waals density-functional calculations. The primary and secondary binding sites for H(2) are confirmed. The low-lying rotational and translational energy levels are 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 H(2) loadings and those measured by inelastic neutron scattering exciting the singlet to triplet (para to ortho) transition in H(2). The H(2) binding energy after zero-point energy correction due to the rotational and translational motions is predicted to be approximately 100 meV in good agreement with the experimental value of approximately 90 meV.
Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA.
Lingzhu
L
Kong
Guillermo
G
Román-Pérez
José M
JM
Soler
David C
DC
Langreth