First-principle study of structure stability and electronic structures of gamma graphyne derivatives
- 物理技术－已发表论文 
通过基于密度泛函理论的第一原理计算,系统研究了gamma石墨炔衍生物的结构稳定性、原子构型和电子性质.gamma石墨炔衍生物的结构是由碳六元环以; 及连接六元环间的碳链组成,碳链上的碳原子数为N=1-6.研究结果表明,碳链上碳原子数的奇偶性对gamma石墨炔衍生物的结构稳定和相应的原子构型、; 电子结构性质具有很大的影响.其奇偶性规律为:当六元环间的碳原子数为奇数时,体系中的碳链均为双键排布,系统呈现金属性;当六元环间的碳原子数为偶数时; ,系统中的碳链形式为单、三键交替排列,体系为直接带隙的半导体.直接带隙的存在能够促进光电能的高效转换,预示着石墨炔在光电子器件中的应用优势.N=; 2,4,6的带隙分布在0.94-0.84; eV之间,带隙的大小与碳链上三键的数量和长度有关.研究表明,将碳原子链引入到石墨烯碳六元环之间,通过控制引入的碳原子个数可以调控其金属和半导体电; 子特性,为设计和制备基于碳原子的可调控s-p杂化的二维材料和纳米电子器件提供了理论依据.A new carbon allotrope-graphyne has attracted a lot of attention in the field of material sciences and condensed-matter physics due to its unique structure and excellent electronic, optical and mechanical properties. First-principles calculations based on the density functional theory (DFT) are performed to investigate the structures, energetic stabilities and electronic structures of gamma-graphyne derivatives (gamma-N). The studied gamma-graphyne derivative consists of hexagon carbon rings connected by onedimensional carbon chains with various numbers of carbon atoms (N = 1-6) on the chain. The calculation results show that the parity of number of carbon atoms on the carbon chains has a great influence on the structural configuration, the structural stability and the electronic property of the system. The gamma-graphyne derivatives with odd-numbered carbon chains possess continuous C-C double bonds, energetically less stable than those with even-numbered carbon chains which have alternating single and triple C-C bonds. The electronic structure calculations indicate that gamma-graphyne derivatives can be either metallic (when N is odd) or direct band gap semiconducting (when N is even). The existence of direct band gap can promote the efficient conversion of photoelectric energy, which indicates the advantage of gamma-graphyne in the optoelectronic device. The band gaps of gamma-2, 4, 6 are between 0.94 eV and 0.84 eV, the gap decreases with the number of triple C-C bonds increasing, and increases with the augment of length of carbon chains in gamma-2, 4, 6. Our first-principles studies show that introducing carbon chains between the hexagon carbon rings of graphene gives us a method to switch between metallic and semiconducting electronic structures by tuning the number of carbon atoms on the chains and provides a theoretical basis for designing and preparing the tunable s-p hybridized two-dimensional materials and nanoelectronic devices based on carbon atoms.