Figure 4: Theoretical results.
(a) The (0001) twist grain boundary (GB) energy in graphite obtained from the APNGB model as a function of twist angle φ (black symbols). The contributions to the GB energy from the elastic and misfit (GSFE) energies are shown by blue and red symbols. The solid black horizontal line shows the GB energy assuming that the graphite crystals are rigid and incommensurate with each other (obtained as the average over the entire GSFE). The inset shows the spatial distribution of the misfit energy in a φ=1° twist grain boundary (dislocations cores are seen as green lines). (b) The results from a plotted over the entire twist angle range (lower black curve) and the corresponding cleavage energy Γ(φ) over the same range based upon the measured values of Γ(φ) (shown as the red line). The green dashed curve shown for comparison, is the typical shape of σ(φ) for a twist GB on the (111) plane of a fcc metal45.
