Distortion of the graphite lattice by a vacancy. A two-dimensional model

Abstract

The method of lattice statics has been used to calculate the atomic displacements around a vacancy and the vacancy‐vacancy interaction energy in graphite. This was achieved by simulating the vacancy by external forces acting radially on the nearest neighbour atoms, and calculating the lattice Green's function for a two‐dimensional model of the graphite structure. Numerical values for the Green's function are presented, and the leading elastic and lattice terms in its asymptotic expansion are derived. Using a value of the external forces obtained from a molecular‐orbital calculation, it is shown that the distortion of the graphite layer by a vacancy is not small, and the resulting relaxation energy is −3.3 eV. The formation area of a vacancy is −0.14 atomic areas, and the mechanical binding energy of a divacancy is 2.0 eV.

Irradiated Carbon Nanostructures as Nanoscopic Pressure Cells

“…We thus exclusively consider irradiation at above-ambient temperatures and explore the experimentally accessible range of temperatures and irradiation rates, 400 K < T < 1200 K and 10 −4 s −1 < Φ < 1 s −1 . The relaxation volume V which governs the stress dependence of the vacancy energy may be estimated from the structural relaxation of atoms around a vacancy, indicating V ≈ 0.14A * d 0 [18]. As initial condition we consider a stress-and defect free structure, i.e., n I i = n V i = 0 and d i = d 0 for all i.…”