A pathway between Bernal and rhombohedral stacked graphene layers with scanning tunneling microscopy
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(a)–(c) Filled-state STM images of the HOPG surface collected at a constant current of 0.1 nA and a tip bias of +0.1 V. (d)–(f) Simulated STM images of graphite extracted from DFT with the top layer shifted horizontally by a fraction of the C–C bond length indicated. (g)–(i) Ball-and-stick structural models showing the locations of the carbon atoms in the top two layers of graphite for a horizontal shift of 0.00, 0.30, and 0.50 bond lengths, respectively.
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(a) DFT energy/atom is plotted (squares) as a function of the top-layer horizontal shift (away from AA stacking), in the direction illustrated by the three ball-and-stick models shown. The pink frame represents the top layer, the green frame the second layer, and the blue frame is the third layer. Inset image: STM data showing graphite- and graphene-like surface charge densities in a single scan. Ball-and stick models are overlaid on the graphite and graphene surfaces to indicate the locations of the carbon atoms as well as the direction and magnitude of the horizontal shift that occurred (the white box behind the models highlights the shift between them). (b) DFT energy/atom is plotted (circles) as a function of the top-layer horizontal shift (toward AA stacking), which is in the direction indicated by the three ball-and-stick models shown. At each step, the atoms were allowed to relax perpendicular to the plane before determining the associated energy and simulating the STM image.
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