单层和双层石墨烯中锂杂质的位置相关紧束缚模型
Position-dependent tight-binding model for Li impurities in monolayer and bilayer graphene
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中文总结 AI 辅助
研究单层和双层石墨烯中锂杂质的电子结构，开发含锂位置依赖性的半经验紧束缚模型，通过拟合确定参数，准确再现费米能级附近电子能带，揭示杂质势空间分布差异，为研究锂杂质提供有效框架。
中文摘要 AI 辅助
锂的吸附和嵌入能显著改变基于石墨烯材料的低能电子特性，这对于理解锂离子在石墨电极中的传输和存储至关重要。本研究中，我们探究了吸附在单层石墨烯（MLG）上以及嵌入AB堆叠双层石墨烯（BLG）中的锂离子的电子结构。为此，我们开发了一个包含锂位置依赖性的半经验紧束缚模型，其参数通过拟合不同构型、高度和超胞尺寸的密度泛函理论计算来确定。该模型准确再现了MLG和BLG费米能级附近的电子能带，并从对称性破缺、谷间混合和带隙打开的角度对杂质诱导的变化给出了清晰解释。我们发现锂离子引入的微扰强烈局域化，且其效应随超胞尺寸增大而减小。拟合参数还揭示了MLG和BLG在杂质势空间分布上的系统差异。所得结果为研究稀锂杂质提供了一个有效框架，也是未来研究石墨烯基材料中锂扩散和杂质诱导输运现象的有用起点。
英文摘要
Lithium adsorption and intercalation can significantly modify the low-energy electronic properties of graphene-based materials, making their characterization relevant for understanding Li-ion transport and storage in graphitic electrodes. In this work, we investigate the electronic structure of a Li ion adsorbed on monolayer graphene (MLG) and intercalated within AB-stacked bilayer graphene (BLG). To this end, we develop a semi-empirical tight-binding model that incorporates Li-position dependence. Its parameters are determined by fitting to density-functional-theory calculations for different configurations, heights, and supercell sizes. The obtained model accurately reproduces the electronic bands near the Fermi level for both MLG and BLG and provides a transparent interpretation of the impurity-induced modifications in terms of symmetry breakings, intervalley mixing, and band-gap openings. We find that the perturbation introduced by the Li ion is strongly localized and that its effect decreases with increasing supercell size. The fitted parameters further reveal systematic differences between MLG and BLG in the spatial profile of the impurity potential. The obtained results provide an efficient framework for studying dilute Li impurities and constitute a useful starting point for future investigations of Li diffusion and impurity-induced transport phenomena in graphene-based materials.
