Graphene nanostructures as tunable storage media for molecular hydrogen

Patchkovskii et al. 10.1073/pnas.0501030102.

Supporting Information

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Supporting Figure 5
Supporting Figure 6
Supporting Table 3
Supporting Table 4
Supporting Table 5
Supporting Figure 7
Supporting Figure 8
Supporting Table 6
Supporting Table 7
Supporting Table 8
Supporting Table 9
Supporting Table 10
Supporting Text
Supporting Figure 9




Supporting Figure 5

Fig. 5. Convergence of the MP2 well depth (Upper) and equilibrium separation between centers of mass of H₂ and C₆H₆ (Lower) for the C_6v H₂/C₆H₆ complex. Open circles indicate the results with no basis set superposition error (BSSE) corrections applied. Closed diamonds give the corresponding values with the counterpoise BSSE correction applied.

Supporting Figure 6

Fig. 6. Ab initio computations (circles) compared to the parameterized LJ potential (solid lines) of H₂ interacting with coronene. (Upper) Movement of H₂ perpendicular to coronene along the C₆ axis. (Lower) Movement of H₂ toward an atom (red) and toward a bond (green) at a distance between molecular plane and center of H₂ of 3.1 Å. Note the difference in the energy scales in Upper and Lower.

Supporting Figure 7

Fig. 7. Results and details of quantum-chemical calculations of H₂ adsorbed at the C₆ site of benzene. Interaction energies for selected ab initio methods with and without counterpoise BSSE corrections, and performance of the parameterized LJ potential.

Supporting Figure 8

Fig. 8. Potential energy surface for H₂ adsorbed on graphite surface. The isosurfaces correspond to potential energy of, respectively, -7.35 (deep blue), -7.13 (blue), -6.0 (teal), -3.0 (green), 0.0 (yellow), and 3.0 (red) kJ/mol. The coordinates are in Å. The carbon atoms of the graphite surface are at z = 0.0 but drawn here at z = 2 Å for clarity. The teal and green PES appear twice, in the short-range and in the long-range area of the potential.

Supporting Figure 9

Fig. 9. Density of states of free H₂ gas (empty box) and H₂ in an external potential. (Upper) Adsorption between two graphite layers at 8-Å distance. (Lower) Adsorption of the graphite surface.

Table 3. MP2/cc-pVTZ energy of the coronene-H₂ complex (kJ/mol) for different positions of the H₂ molecule, relative to infinitely separated coronene and H₂

Cartesian coordinates of the coronene molecule are given in Table 8. R is the distance between the centres of mass in Å. E(CP) included the counterpoise correction for the basis set superposition error. E(no CP) is the energy difference without the correction.

Table 4. Scans of the coronene-H₂ PES along the X and Y directions (Table 8)

Interaction energies E_X and E_Y, respectively, are given in kJ/mol. H₂ is always moved along one axis, whereas the other displacement is kept at zero. The coordinates in Z direction are always kept constant. Coordinate of H₂ atoms on Z axis:

Table 5. van der Waals potential parameters, fitted to MP2/cc-pVTZ results in Tables 3 and 4

Potential parameters for carbon atom–H₂ interactions. A and C₆ are given in kJ/mol, 1/a and r in Å.

Table 6. Cartesian coordinates of benzene atoms used in evaluating the potential energy surface, in Å

Table 7. MP2/cc-pVTZ energies of the benzene-H₂ complex (kJ/mol) for different positions of the H₂, relative to infinitely separated benzene and H₂

Cartesian coordinates of the benzene molecule are given in Table 6. R is the distance between the centers of mass in Å. E(CP) included the counterpoise correction for the basis set superposition error. E(no CP) is the energy difference without the correction.

Table 8. Cartesian coordinates of coronene atoms used in evaluating the PES, in Å