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arXiv 1707.09059cond-mat.mtrl-sci
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石墨烯的扭转势由拟合到DFT结果导出

A Torsional potential for graphene derived from fitting to DFT results

Georgios D. Chatzidakis, George Kalosakas, Zacharias G. Fthenakis, Nektarios N. Lathiotakis

摘要:

我们提出了一个简单的扭转势石墨烯,以准确地描述其出平面变形。通过适当的拟合与适当的DFT计算得到的参数的潜在的变形能量的石墨烯片折叠在两个不同的折叠轴,沿扶手椅或沿Z字形方向。去除弯曲角度的能量贡献,使用先前引入的角度弯曲势,我们分离出纯扭转变形能量,然后将其拟合到简单的扭转力场。所提出的面外扭转势可以准确地拟合高达0.5 rad的相对较大扭转角的变形能。为了测试我们提出的潜力,我们将其应用到一个单一的碳原子的石墨烯平面的垂直位移的问题,并比较所获得的变形能与相应的DFT计算。在这两种情况下,对于高达约0.5 $Å$的位移,形变能对被拉碳原子的垂直位移的依赖性是不可区分的。所提出的潜力是适用于其他sp $^2$碳结构。

英文摘要:

We present a simple torsional potential for graphene to accurately describe its out-of-plane deformations. The parameters of the potential are derived through appropriate fitting with suitable DFT calculations regarding the deformation energy of graphene sheets folded around two different folding axes, along an armchair or along a zig-zag direction. Removing the energetic contribution of bending angles, using a previously introduced angle bending potential, we isolate the purely torsional deformation energy, which is then fitted to simple torsional force fields. The presented out-of-plane torsional potential can accurately fit the deformation energy for relatively large torsional angles up to 0.5 rad. To test our proposed potential, we apply it to the problem of the vertical displacement of a single carbon atom out of the graphene plane and compare the obtained deformation energy with corresponding DFT calculations. The dependence of the deformation energy on the vertical displacement of the pulled carbon atom is indistinguishable in these two cases, for displacements up to about 0.5 $Å$. The presented potential is applicable to other sp$^2$ carbon structures.

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