Ripples in isotropically compressed graphene
Ripples in isotropically compressed graphene
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DOI：
10.1016/j.commatsci.2019.109422
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发表时间：
2020-02-15
影响因子：
3.3
通讯作者：
Harrison, Nicholas M.
中科院分区：
文献类型：
--
作者：
Abualnaja, Faris;Hildebrand, Mariana;Harrison, Nicholas M.
基于密度泛函摄动理论，证明了石墨烯的各向同性压缩会引起结构变形。由虚频率声子模式表示的静态不稳定性是由石墨烯片的各向同性压缩应变在高对称性γ - k（之字形）和γ - m（扶手椅）方向上引起的。不稳定模式（波纹）的波长与应变的大小直接相关，并且对二维晶格中的传播方向不敏感。这些计算进一步表明，波纹的形成能量在低应变下是各向同性的，而在大应变下则是各向异性的。这是石墨烯弹性特性的结果，它取决于方向和应变。在准谐波近似中，结合分子吸附能强烈依赖于曲率的观察结果，提出了一种生成有序覆盖层的策略，以调整石墨烯的功能特性。
An isotropic compression of graphene is shown to induce a structural deformation on the basis of Density Functional Perturbation Theory. Static instabilities, indicated by imaginary frequency phonon modes, are induced in the high symmetry Gamma-K (zigzag) and Gamma-M (armchair) directions by an isotropic compressive strain of the graphene sheet. The wavelength of the unstable modes (ripples) is directly related to the magnitude of the strain and remarkably insensitive to the direction of propagation in the 2D lattice. These calculations further suggest that the formation energy of the ripple is isotropic for lower strains and becomes anisotropic for larger strains. This is a result of graphene's elastic property, which is dependent on direction and strain. Within the quasi-harmonic approximation this is combined with the observation that molecular adsorption energies depend strongly on curvature to suggest a strategy for generating ordered overlayers in order to tune the functional properties of graphene.