双层石墨烯吸附碱金属原子的第一性原理研究
First-principles study of alkali metal adsorptions on bilayer graphene

基于密度泛函的第一性原理方法，研究了Li、Na、K和Rb碱金属原子吸附在双层石墨烯(BLG)表面的吸附能、迁移行为、电子性能. 研究发现，Li和Na原子在BLG表面吸附易形成团簇，K和Rb原子能够分散吸附. 碱金属原子在BLG表面的扩散能垒随原子半径的增加而减小. 碱金属原子吸附使电子部分转移至BLG，使体系Fermi能级贯穿导带，表现出金属性. 电荷密度差和电荷转移的分析表明，Li、Na、K和Rb与BLG表面以离子键结合.
Using the first-principles method based on the density functional theory, the adsorption energies, migration processes and electronic properties for the Li, Na, K and Rb adsorbed on the bilayer graphene (BLG) were calculated. The calculated adsorption energies indicate that both Li and Na atoms tend to aggregate into clusters, and the K and Rb atoms can dispersive on the BLG. The energy barriers for alkali-metal atoms migration decrease with the increasing of the atomic radius. The adsorption systems exhibit metallic character since the Fermi level shifts up into the conduction band due to the electrons transfer from adatoms to the BLG. Analysis of the charge density differences and electronic structures of these adsorption systems shows that ionic bond takes place between the alkali-metal atoms (Li, Na, K and Rb) and the BLG.