Du Hui, Li Guoling, Chen Jiao, Lv Zhenlong, Chen Yuanzheng, Liu Shijie
Henan Key Laboratory of Photoelectric Energy Storage Materials and Applications, School of Physics and Engineering, Henan University of Science and Technology, Luoyang, 471023, China.
Phys Chem Chem Phys. 2020 Sep 21;22(35):20107-20113. doi: 10.1039/d0cp02169e. Epub 2020 Sep 2.
Although a number of interesting physical properties such as a negative Poisson's ratio (NPR) and Dirac semimetal (DS) properties have been recently predicted in two-dimensional (2D) materials, the realization of a 2D material that exhibits both of these DS and NPR features has rarely been reported. Here by adopting particle swarm optimization (PSO) algorithms combined with first-principles methods, we successfully construct a novel SiO monolayer (Pmna), the dynamic and thermal stability of which was characterized using phonon spectrum calculations and molecular dynamics simulations. In particular, Young's modulus and Poisson's ratio calculations showed that the Pmna monolayer exhibits high mechanical anisotropy with an in-plane NPR originating from its puckered atomic arrangement. More notably, the band structure of the Pmna monolayer possesses zero bandgap with four Dirac cones in its first Brillouin zone, exhibiting a DS feature. From the calculations of orbital-resolved band structures, the Dirac cone was revealed to originate from the orbital hybridization of Si and O atoms. The Pmna monolayer is the first 2D structure in the Si-O system that has both an NPR and Dirac semi-metal properties, providing a new model for exploring 2D multifunctional materials.
尽管最近在二维（2D）材料中预测了许多有趣的物理性质，如负泊松比（NPR）和狄拉克半金属（DS）性质，但很少有报道实现同时具有这两种DS和NPR特征的二维材料。在此，通过采用粒子群优化（PSO）算法结合第一性原理方法，我们成功构建了一种新型的SiO单层（Pmna），利用声子谱计算和分子动力学模拟对其动力学和热稳定性进行了表征。特别是，杨氏模量和泊松比计算表明，Pmna单层表现出高机械各向异性，其面内NPR源于其褶皱的原子排列。更值得注意的是，Pmna单层的能带结构在其第一布里渊区具有零带隙和四个狄拉克锥，呈现出DS特征。从轨道分辨能带结构的计算结果来看，狄拉克锥源于Si和O原子的轨道杂化。Pmna单层是Si-O系统中第一个同时具有NPR和狄拉克半金属性质的二维结构，为探索二维多功能材料提供了一个新模型。
