Figure 4: Properties of adsorbed molecular hydrogen at the Cu(I) sites.
From: Capture of heavy hydrogen isotopes in a metal-organic framework with active Cu(I) sites
(a) The interaction potential U of H2 as function of distance R of the molecular centre of H2 from the Cu(I) site. The curve fits to a Morse potential, and the vibrational energy levels E0 (zero point energy) and E1 (first excitation) are given for the adsorbed hydrogen isotopologues H2 (red), D2 (black) and T2 (blue). (b) Probability density 
of the adsorbed hydrogen isotopologues (same colour code). Probability values are given as dotted vertical lines. (c) Intramolecular H2 distance r as function of R. (d) Frequency of the vibrational intramolecular stretching mode νr of the adsorbed isotopologues. In c,d, the value for free H2 (green dash-dotted line) are given for comparison.
