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Instabilities in carbon nanocone stacks
Carbon ( IF 10.5 ) Pub Date : 2018-02-01 , DOI: 10.1016/j.carbon.2017.11.023
Arindam Raj , Aningi Mokhalingam , Shakti S. Gupta

Abstract Possessing remarkable electronic, mechanical and optical properties, pristine single-walled carbon nanocones (CNCs) are envisioned here to be pulled-out co-axially from a nanocone stack. The process is simulated using molecular mechanics (MM) and dynamics (MD) employing MM3 and REBO + LJ potentials, respectively. During pulling-out, rim of the lowermost cone is constrained while the tip of the outermost cone is displaced axially from its equilibrium, quasi-statically in case of MM and by prescribing velocity of 0.1 A/pico-sec in case of MD. During pulling-out, at a critical distance, the top cone abruptly breaks the axial symmetry with its wall deforming considerably outward. The source of this instability is building-up of compressive circumferential strain in the wall with increasing displacement; a competition between stretching and van der Waal's energy terms of the system. Interestingly, during reversal of the pulling-out process, the system is found to trace a different equilibrium path. Further, in a few-walled CNCs if the tip of the top-most cone is compressed from its equilibrium position, the stack inverts completely by breaking axial symmetry aided by snap-through buckling in segments of the periphery. Irrespective of apex angle, hydrogen passivation, temperature and potential used, the aforementioned observations are found to be intrinsic to the system.

中文翻译:

碳纳米锥堆叠的不稳定性

摘要 原始的单壁碳纳米锥 (CNC) 具有卓越的电子、机械和光学特性,可以从纳米锥堆栈中同轴拉出。该过程分别使用分子力学 (MM) 和动力学 (MD) 分别采用 MM3 和 REBO + LJ 势进行模拟。在拉出过程中,最下锥体的边缘受到约束,而最外锥体的尖端从其平衡轴向位移,在 MM 的情况下是准静态的,在 MD 的情况下,规定速度为 0.1 A/皮秒。在拉出过程中,在临界距离处,顶锥突然打破轴对称,其壁向外变形明显。这种不稳定性的根源是随着位移的增加在壁中形成压缩周向应变;拉伸与系统的范德华能量项之间的竞争。有趣的是,在拉出过程的逆转过程中,发现系统跟踪不同的平衡路径。此外,在少数壁 CNC 中,如果最顶部锥体的尖端从其平衡位置被压缩,则堆栈会通过在外围部分中的快速屈曲帮助下破坏轴向对称性而完全倒置。不管使用的顶角、氢钝化、温度和电位如何,发现上述观察结果是系统固有的。通过在外围部分的快速弯曲的帮助下打破轴向对称,堆叠完全倒置。不管使用的顶角、氢钝化、温度和电位如何,发现上述观察结果是系统固有的。通过在外围部分的快速弯曲的帮助下打破轴向对称,堆叠完全倒置。不管使用的顶角、氢钝化、温度和电位如何,发现上述观察结果是系统固有的。
更新日期:2018-02-01
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