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锯齿型延伸修饰扶手椅边缘三角形石墨烯量子点磁性的第一性原理研究
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Abstract:
本文采用第一性原理计算方法研究了锯齿型延伸对扶手椅边缘三角形石墨烯量子点磁性的物理影响。研究结果表明，当向三角形石墨烯量子点的扶手椅边缘添加两个或三个锯齿型延伸时，大部分修饰结构的基态都符合Lieb定理，但少部分修饰结构违背了Lieb定理，后者可以归因于最高占据分子轨道和最低未占据分子轨道之间较小的能量差。此外，我们还发现添加锯齿型延伸后，一部分修饰结构的基态仍然保持低自旋态，而另一部分结构的基态从低自旋态变成了高自旋态。我们的发现对于调控具有扶手椅边缘石墨烯量子点的磁学特性具有重要的意义。
Using first-principles calculations, we investigate the effect of zigzag extensions on the magnetic properties of triangular graphene quantum dot with armchair edges. The results show that when two or three zigzag extensions are added to the armchair edges of triangular graphene quantum dot, the ground states of most modified structures conform to the Lieb’s theorem, while some structures violate the Lieb’s theorem, which can be attributed to the small energy difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). In addition, we find that the ground states of partial modified structures remain in the low-spin state, while the others change from a low-spin state to a high-spin state. Our findings have important im-plications for manipulating the magnetism of graphene quantum dot with armchair edges.
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