尺寸和边界形貌对三角锯齿型石墨烯量子点的磁性影响

采用约束路径量子蒙特卡罗计算方法和基于密度泛函理论的第一性原理数值计算方法，研究了不同尺寸的规则三角锯齿型石墨烯量子点（ZZ）和边界重构后的三角锯齿型石墨烯量子点（ZZST）的磁学特性和电子结构特征．2种方法的计算结果均表明：在所有尺寸下的ZZ的基态均处于铁磁态；当边界重构后，除了尺寸很小的外，其他尺寸的基态均处于反铁磁态．通过Drool^3软件包计算费米能级附近的上下自旋电子态密度分布，发现ZZ在费米能级附近出现明显自旋向上和自旋向下的态密度分布的劈裂，边界重构后费米能级附近的自旋极化被弱化，表明不规则的边界对石墨烯量子点的磁性具有抑制作用．

Effect of the size and edge reconstruction on magnetism in triangular graphene quantum dots with zigzag edges

The magnetic and electronic structure characteristics of triangular graphene quantum dots with regular zigzag edges （ZZ） and irregular pentagon-heptagon zigzag edges （ZZ57） had been systematically investigated using Constrained-Path Monte Carlo and ab initio methods under different sizes. The results obtained by the two methods consistently were shown that： the ground state of ZZ configuration for all sizes lied in the ferromagnetic state; on the contrary, the ZZ~7 configuration lied in the antiferromagnetic state with the exception of the case with a small size. In addition, the up- and down-spin electronic density of states near the Fermi level were investigated through the DmoP package. The results were shown that the up- and down-spin states were split around the Fermi level, while this splitting was weakened for the ZZsr configuration. Our results indicated that the reconstructed edges suppressed the spin polarization and magnetism in triangular grapheme quantum dots.