石墨烯内聚能的密度泛函理论研究

DFT Studies on the Cohesive Energy of Graphene

摘要: 本文基于第一性原理和密度泛函理论，在局域密度近似以及广义梯度近似下，研究了石墨烯的几何结构和内聚能。石墨烯是由碳原子组成的六角形结构，通过密度泛函理论的计算程序，计算得到了石墨烯体系的总能量，以及孤立碳原子体系的总能量。计算结果表明：石墨烯的内聚能约为−9~−10 eV，对于不同的计算方法及参数，得到的内聚能总为负，这表明石墨烯结构相对于孤立的碳原子来说能量更低。因此相比于孤立的碳原子来说，吸引的相互作用使得系统更倾向于形成石墨烯的结构，说明石墨烯的结构是稳定的。通过本计算模拟研究可对今后石墨烯的结构以及新型结构(例如转角石墨烯)的性能研究及应用发展提供理论参考。

Abstract: In this paper, the geometric structure and cohesive energy of graphene are investigated under local density approximation (LDA) as well as generalized gradient approximation (GGA) based on first principles and density functional theory. Graphene is a hexagonal structure composed of carbon atoms. The total energy of the graphene system and the total energy of the isolated carbon atom system are calculated by the density functional theory. The calculation results show that the cohesive energy of graphene is about -9 to -10eV, and for different calculation methods and parameters, the cohesive energy obtained is always negative, which indicates that the graphene structure has lower energy relative to the isolated carbon atoms. Therefore, the attractive interaction makes the system more inclined to form the graphene structure compared to the isolated carbon atoms, indicating that the graphene structure is stable. This computational simulation study can provide a theoretical reference for the future development of graphene structures, as well as the performance studies and applications of novel structures (e.g., twist graphene).