Fig. 4
From: Raman evidence for pressure-induced formation of diamondene
Geometries for diamondene formation. a Initial (left) and converged (right) geometries for the case in which the distance between graphene layers is initially set to d = 2.8 Å. Blue, red, and gray spheres represent H, O, and C atoms, respectively. The vertical arrows indicate the forces applied by the PTM (F) and the substrate underneath (FS). Upon relaxation, the distance d decreases to 2.2 Å, still too long to characterize a covalent interaction between layers. b A second calculation in which the initial distance d was set to 2.7 Å. After relaxation (right), the diamondene forms. The C–C interlayer bond lengths become 1.66 Å, and the constrained forces are negligible
