Molecular dynamics simulations have been used to study the structural modification of graphene by electron irradiation. The authors used the Monte Carlo method to introduce the interaction between incident electrons and carbon atoms in graphene. Then, the effects of electron energy and incident angle on irradiation defects in single-layer graphene were studied, and the cutting of single-layer graphene using different methods of electron irradiation was compared. Following this, the authors simulated the process of single atom chain formation from single-layer graphene using electron irradiation. They also demonstrated the formation of three-dimensional structures, such as tubular structures and nanotube junctions, in bilayer graphene by electron irradiation. The simulations show the capability of structural modification of graphene to a variety of nanostructures by electron irradiation.

Molecular dynamics simulations were performed to study defect formation and transformation in graphene under electron irradiation. The single-vacancy was the most frequently formed defect and the number of defects did not depend on the defect formation energy for normal incidence. The single-vacancy transformed to other types of defects and migrated in graphene by heating. The recovery energies of adatom-vacancy and pentagon–heptagon defects were relatively small. The Stone–Wales defect was the most stable, and did not easily recover. In the single atomic chain formation process from graphene by electron irradiation, competition between defect formation by electron collision and the recovery by heating was observed.

A molecular dynamics (MD) simulation was performed to study the interaction volume of electron beam in carbon nanomaterials. The interaction between incident electron and carbon atom in the target materials during electron irradiation is introduced by the relativistic binary collision theory. The motion of each atom in the material under electron irradiation is calculated with the MD simulation. The primary energy dependence of the interaction volume in the carbon nanotube and the multi-layered graphene are studied. The secondary damages caused by the knock-on atoms are also discussed.

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