Figure 3. Left: 2D (r,Z) cuts of the PES (A,D,G) computed for the three molecular adsorption
geometries. Contour lines separate 0.2 eV energy intervals, solid lines are used for E ≥ 0 eV and
dashed lines for E < 0 eV. Circles indicate all the (first order) saddle points. The black circles
represent the entrance channel barriers for molecular adsorption (Eent ) and the white circles are

2D saddle-points that are not real first order saddle-points in the 6D space (see text for details).
Some details about the molecular adsorption geometries considered are reported as insets in the
related plots. Right: top view (B, E, H) and side view (C, F, I) of the adsorption states. The 2D
PES cuts are shown for the geometries bridge-hollow-tilted (A, B, C), hollow-parallel (D,E,F), and
for top-vertical adsorption (G,H,I). The first layer atoms are shown in gray and the second layer
atom closest to the molecule is shown in brown, the nitrogen atoms are shown in blue.

The data used to interpolate these plot are in folder ../Tab04