The package is freely available at: http://lin.uestc.edu.cn/server/pseknc.

Time-dependent density functional theory combined with Ehrenfest dynamics are employed to calculate electronic energy loss of energetic ions in two-dimensional graphene and white graphene (BN) targets. Special attention is paid to the effects of different electronic structures on their stopping power. Our results show that the energy transferred to the graphene target is much larger than to BN for both H(+) and He(2+) projectiles. Since the energy is mainly deposited into the electronic degree of freedom, it means that the electronic structure of the target plays an important role in determining the collision process. Our analysis indicates that more excited electrons are observed in graphene compared to BN. At low energies, a velocity proportional relation is found in the electronic energy loss of H(+) and He(2+) in both graphene and BN. In particular, a threshold velocity is observed for He(2+). Finally, we have compared the energy transfer from neutral and charged projectiles when they collide with graphene and BN and the results show that charged projectiles damage the targets more severely.

Although ion beam technology has frequently been used for introducing defects in graphene, the associated key mechanism of the defect formation under ion irradiation is still largely unclear. We report a systematic study of the ion irradiation experiments on SiO2-supported graphene, and quantitatively compare the experimental results with molecular dynamic simulations. We find that the substrate is, in fact, of great importance in the defect formation process, as the defects in graphene are mostly generated through an indirect process by the sputtered atoms from the substrate.