论文标题
二维碳化硅的量子效应
Quantum effects in two-dimensional silicon carbide
论文作者
论文摘要
二维（2D）碳化硅是一种新兴的直接带隙半导体，最近合成，具有潜在的电子设备和光电上的应用。在这里，我们通过在25至1500〜K的温度范围内通过路径综合分子动力学（PIMD）模拟研究了该2D材料中的核量子效应。原子间相互作用是由适合密度功能计算的紧密结合的哈密顿量建模的。量子原子离域结合振动模式的非谐调性会导致2D SIC的结构和热性质的变化，我们通过比较PIMD的结果与源自经典分子动力学模拟的结果进行量化，以及与量子谐波近似所给出的结果。发现核量子效应在结构特性（例如层面积和原子间距离）中是可观的。此外，我们考虑了SIC纸的{\ em Real}区域，该区域考虑到有限温度下的弯曲和波纹。在量子原子动力学的背景下，讨论了该区域和平面区域之间的差异。弯曲常数（$κ= 1.0 $ eV）和静液压压缩的2D模量（$ b_ {xy} $ = 5.5 eV/Å$^2 $）明显低于石墨烯的相应值。这项研究为对2D SIC的弹性和机械性能有了更深入的了解铺平了道路。
Two-dimensional (2D) silicon carbide is an emergent direct band-gap semiconductor, recently synthesized, with potential applications in electronic devices and optoelectronics. Here, we study nuclear quantum effects in this 2D material by means of path-integral molecular dynamics (PIMD) simulations in the temperature range from 25 to 1500~K. Interatomic interactions are modeled by a tight-binding Hamiltonian fitted to density-functional calculations. Quantum atomic delocalization combined with anharmonicity of the vibrational modes cause changes in structural and thermal properties of 2D SiC, which we quantify by comparison of PIMD results with those derived from classical molecular dynamics simulations, as well as with those given by a quantum harmonic approximation. Nuclear quantum effects are found to be appreciable in structural properties such as the layer area and interatomic distances. Moreover, we consider a {\em real} area for the SiC sheet, which takes into account bending and rippling at finite temperatures. Differences between this area and the in-plane area are discussed in the context of quantum atomic dynamics. The bending constant ($κ= 1.0$ eV) and the 2D modulus of hydrostatic compression ($B_{xy}$ = 5.5 eV/Å$^2$) are clearly lower than the corresponding values for graphene. This study paves the way for a deeper understanding of the elastic and mechanical properties of 2D SiC.
