Conclusions
In this work, two adatom defect structures of Cap-(9, 0)-Def [6, 6] and Cap-(9, 0)-Def [5, 6] were studied using first principles. The calculation results show that the adatom enlarges the geometric structure. The electronic properties further demonstrate that the adatom induces the generation of spin polarization, and the spin polarization phenomenon is different for different adsorption positions. MOs analysis shows that the single-electron occupied MOs are mainly contributed by the carbon atom at zigzag edge and the adatom at the cap. Furthermore, the electron density reveals that the adsorption position causes the difference in electron accumulation. The research will promote the regulation of spin polarization of carbon materials.