Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-11-1302 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
J Phys Chem B. 2009 Dec 31;113(52):16526-36. doi: 10.1021/jp9069866.
In this work, we theoretically investigated the friction mechanism of hexagonal MoS(2) (a well-known lamellar compound) using a computational chemistry method. First, we determined several parameters for molecular dynamics simulations via accurate quantum chemistry calculations and MoS(2) and MoS(2-x)O(x) structures were successfully reproduced. We also show that the simulated Raman spectrum and peak shift on X-ray diffraction patterns were in good agreement with those of experiment. The atomic interactions between MoS(2) sheets were studied by using a hybrid quantum chemical/classical molecular dynamics method. We found that the predominant interaction between two sulfur layers in different MoS(2) sheets was Coulombic repulsion, which directly affects the MoS(2) lubrication. MoS(2) sheets adsorbed on a nascent iron substrate reduced friction further due to much larger Coulombic repulsive interactions. Friction for the oxygen-containing MoS(2) sheets was influenced by not only the Coulomb repulsive interaction but also the atomic-scale roughness of the MoS(2)/MoS(2) sliding interface.
在这项工作中，我们使用计算化学方法从理论上研究了六方 MoS(2)（一种众所周知的层状化合物）的摩擦机理。首先，我们通过精确的量子化学计算确定了分子动力学模拟的几个参数，成功再现了 MoS(2)和 MoS(2-x)O(x)结构。我们还表明，模拟的拉曼光谱和 X 射线衍射图案上的峰位移与实验结果非常吻合。通过混合量子化学/经典分子动力学方法研究了 MoS(2)片之间的原子相互作用。我们发现，不同 MoS(2)片之间两层硫之间的主要相互作用是库仑排斥，这直接影响 MoS(2)的润滑。吸附在初生铁基底上的 MoS(2)片由于更大的库仑排斥相互作用进一步降低了摩擦。含氧 MoS(2)片的摩擦不仅受库仑排斥相互作用的影响，还受 MoS(2/ MoS(2)滑动界面的原子尺度粗糙度的影响。
