石墨烯在h-BN上：对齐还是不对齐？
Graphene on h-BN: to align or not to align?
摘要：
石墨烯与诸如{ \it h}-BN的无公度晶体基底之间的接触强度、粘附力和摩擦力取决于它们的相对取向角$θ$。成熟的Novaco-McTague（NM）理论预测，对于硬块体{ \it h}-BN晶体表面上的单层石墨烯，小的自发未对准，这里为$θ_{NM}$ \，$\simeq$\，0.45度，如果实现，则其将与除了机械性质之外的许多电子性质相关。由于实验平衡是很难实现的，我们询问理论上的对齐或错位的模拟的基础上可靠的国家的最先进的原子间的力场。起初令人惊讶的是，我们发现了$θ= 0$的令人信服的证据，即，在{ \it h}-BN上石墨烯的平衡态下的完全能量驱动的排列。有两个因素导致了这种对NM理论的偏离。首先，石墨烯不是平坦的，在{ \it h}-BN上形成长波长的面外缺陷。第二，{ \it h}-BN不硬，通过伴随界面莫尔结构的平面收缩/膨胀来释放其接触应力。通过人为地迫使石墨烯保持平坦并且{ \it h}-BN保持刚性的重复模拟确实产生了与预期的类似于$θ_{NM}$的平衡未对准。随后的滑动模拟表明，石墨烯在{ \it h}-BN上的摩擦力在人工冷冻状态下很小并且基本上与未对准无关，在更现实的波纹状、应变调制的对准状态下强烈增加。
英文摘要：
The contact strength, adhesion and friction, between graphene and an incommensurate crystalline substrate such as {\it h}-BN depends on their relative alignment angle $θ$. The well established Novaco-McTague (NM) theory predicts for a monolayer graphene on a hard bulk {\it h}-BN crystal face a small spontaneous misalignment, here $θ_{NM}$\,$\simeq$\,0.45 degrees which if realized would be relevant to a host of electronic properties besides the mechanical ones. Because experimental equilibrium is hard to achieve, we inquire theoretically about alignment or misalignment by simulations based on dependable state-of-the-art interatomic force fields. Surprisingly at first, we find compelling evidence for $θ= 0$, i.e., full energy-driven alignment in the equilibrium state of graphene on {\it h}-BN. Two factors drive this deviation from NM theory. First, graphene is not flat, developing on {\it h}-BN a long-wavelength out-of-plane corrugation. Second, {\it h}-BN is not hard, releasing its contact stress by planar contractions/expansions that accompany the interface moiré structure. Repeated simulations by artificially forcing graphene to keep flat, and {\it h}-BN to keep rigid, indeed yield an equilibrium misalignment similar to $θ_{NM}$ as expected. Subsequent sliding simulations show that friction of graphene on {\it h}-BN, small and essentially independent of misalignments in the artificial frozen state, strongly increases in the more realistic corrugated, strain-modulated, aligned state.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
