Modeling vacancies and hydrogen impurities in graphene: A molecular point of view
Modeling vacancies and hydrogen impurities in graphene: A molecular point of view
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DOI：
10.1016/j.physleta.2008.08.014
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发表时间：
2008-09-29
影响因子：
2.6
通讯作者：
Vilardi, R.
中科院分区：
文献类型：
--
作者：
Forte, G.;Grassi, A.;Vilardi, R.
我们遵循“分子”的方法来研究石墨烯中的杂质效应。这被认为是无限大苯环簇的极限情况。因此，我们研究了几个碳簇，随着尺寸的增加，从非那烯，包括三个苯环，到晕苯61，有61个苯环。考虑的杂质是化学吸附的H原子，空位，和取代质子。我们使用STO-3G基组进行了HF和UHF计算。随着在不存在杂质的情况下簇的大小增加，我们发现一个减小的能隙，这里定义为HOMO-LUMO差。在H化学吸附或空位的情况下，差距不会明显减小，而在取代质子的情况下，间隙显著减小。杂质的存在总是引起HOMO能级附近的态密度的增加。我们发现零模只在质子替代的情况下。与实验一致，我们发现，化学吸附的H，替代质子，和C原子附近的空位获得磁矩。还讨论了石墨烯簇与新型电子器件设计的相关性。(C)2008 Elsevier B. V.保留所有权利。
We have followed a 'molecular' approach to study impurity effects in graphene. This is thought as the limiting case of an infinitely large cluster of benzene rings. Therefore, we study several carbon clusters, with increasing size, from phenalene, including three benzene rings, up to coronene 61, with 61 benzene rings. The impurities considered were a chemisorbed H atom, a vacancy, and a substitutional proton. We performed HF and UHF calculations using the STO-3G basis set. With increasing cluster size in the absence of impurities, we find a decreasing energy gap, here defined as the HOMO-LUMO difference. In the case of H chemisorption or a vacancy, the gap does not decrease appreciably, whereas it is substantially reduced in the case of a substitutional proton. The presence of an impurity invariably induces an increase of the density of states near the HOMO level. We find a zero mode only in the case of a substitutional proton. In agreement with experiments, we find that both the chemisorbed H, the substitutional proton, and the C atom near a vacancy acquire a magnetic moment. The relevance of graphene clusters for the design of novel electronic devices is also discussed. (C) 2008 Elsevier B.V. All rights reserved.