Figure 2: Energy of vertical nanowall versus horizontal nanosheet.
From: Atomic scale simulation of carbon nanotube nucleation from hydrocarbon precursors

Potential energies per atom (solid circles) of the pure Ni55 nanocluster, Ni55C8 nickel carbide cluster, totally (C40H12) and partially (C40H8) H-terminated graphene walls as well as a C40 graphene sheet on the Ni55C8 nickel carbide; interaction energies (open circles) between the C40H12 or C40H8 wall and the Ni55C8 nanocluster, as well as between the C40 graphene sheet and the Ni55C8 nanocluster.