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.