  Hydrogen adsorption by the metal organic framework (MOF) structure
Zn2(BDC)2(TED) is investigated using a combination of experimental and
theoretical methods. By use of the nonempirical van der Waals
density-functional (vdW-DF) approach, it is found that the locus of deepest H2
binding positions lies within two types of narrow channel. The energies of the
most stable binding sites, as well as the number of such binding sites, are
consistent with the values obtained from experimental adsorption isotherms and
heat of adsorption data. Calculations of the shift of the H-H stretch frequency
when adsorbed in the MOF give a value of approximately -30 cm-1 at the
strongest binding point in each of the two channels. Ambient temperature
infrared absorption spectroscopy measurements give a hydrogen peak centered at
4120 cm-1, implying a shift consistent with the theoretical calculations.
