Graphane is a layered material consisting of a sheet of hydrogenated graphene, with a C:H ratio of 1:1. We study isotopic effects in the properties of chair graphane, where H atoms alternate in a chairlike arrangement on both sides of the carbon layer. We use path-integral molecular dynamics simulations, which allows one to analyze the influence of nuclear quantum effects on equilibrium variables of materials. Finite-temperature properties of graphane are studied in the range 50–1500 K as functions of the isotopic mass of the constituent atoms, using an efficient tight-bonding potential. Results are presented for kinetic and internal energy, atomic mean-square displacements, fluctuations in the C–H bond direction, plus interatomic distances and layer area. At low temperature, substituting ¹³C for ¹²C gives a fractional change of −2.6 × 10⁻⁴ in C–C distance and −3.9 × 10⁻⁴ in the graphane layer area. Replacing ²H for ¹H causes a larger fractional change in the C–H bond of −5.7 × 10⁻³. The isotopic effect in C–C bond distance increases (decreases) by applying a tensile (compressive) in-plane stress. These results are interpreted in terms of a quasiharmonic approximation for the vibrational modes. Similarities and differences with isotopic effects in graphene are discussed.

石墨烷是一种层状材料，由一片氢化石墨烯组成，C:H 比为 1:1。我们研究了椅子石墨烷特性中的同位素效应，其中 H 原子在碳层两侧以椅子状排列交替。我们使用路径积分分子动力学模拟，它允许人们分析核量子效应对材料平衡变量的影响。石墨烷的有限温度特性在 50-1500 K 范围内作为组成原子的同位素质量的函数进行研究，使用有效的紧密键合势。结果显示为动能和内能、原子均方位移、C-H 键方向的波动以及原子间距离和层面积。低温时，用¹³ ℃代替¹² C在 C-C 距离中给出了 -2.6 × 10 ^-4的分数变化，在石墨烷层区域中给出了-3.9 × 10 ^-4的分数变化。将² H替换为¹ H 会导致 -5.7 × 10 ^-3的 C-H 键发生较大的变化。通过施加拉伸（压缩）面内应力，C-C 键距的同位素效应会增加（减少）。这些结果是根据振动模式的准谐波近似来解释的。讨论了石墨烯中同位素效应的异同。