Peng Jingjing, Li Wei, Wang Yu, Yu Xiaoyan, Liu Junming, He Qinyu
Guangdong Engineering Technology Research Center of Efficient Green Energy and Environment Protection Materials, South China Normal University, Guangzhou, 510006, China.
School of Physics and Telecommunication Engineering, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou, 510006, China.
J Mol Model. 2017 Oct 23;23(11):319. doi: 10.1007/s00894-017-3494-6.
To explore the structural and electronic properties of SnSe under pressure, we applied hydrostatic pressure from 0 to 8 GPa to a fully relaxed SnSe cell sample based on plane-wave pseudopotential density functional theory. The calculated results indicate that the structure of SnSe changes gradually from an irregular zigzag structure with low symmetry to a B1-like structure with regular arrangement and high symmetry under pressure. The lattice parameters and cell volume of SnSe decrease monotonically as the applied pressure increases. The energy band gap of SnSe becomes narrow under pressure and is finally closed at 6.1 GPa. Moreover, we found that SnSe exhibits non-magnetic and semi-metallic features based on analyzing its electronic state density and spin state density. This can be attributed to the decrease in the lattices constants and the enhancement of the Sn-Se bond interaction under pressure, which causes the density of electronic states to increase near the Fermi surface. Finally, the charge distribution between Se-Sn-Se along the c-axis changes gradually from asymmetric to symmetric as the pressure is increased to 6.1 GPa and beyond. This implies that enhancement of the structure symmetry of SnSe can lead to a symmetrical distribution of charges, which further affects the bonding characteristics of the Sn-Se bond.
为了探究压力下SnSe的结构和电子性质，我们基于平面波赝势密度泛函理论，对一个完全弛豫的SnSe晶胞样品施加了从0到8吉帕的静水压力。计算结果表明，SnSe的结构在压力作用下逐渐从低对称性的不规则之字形结构转变为排列规则且对称性高的类B1结构。随着施加压力的增加，SnSe的晶格参数和晶胞体积单调减小。SnSe的能带隙在压力下变窄，最终在6.1吉帕时关闭。此外，通过分析其电子态密度和自旋态密度，我们发现SnSe呈现出非磁性和半金属特性。这可归因于压力下晶格常数的减小以及Sn - Se键相互作用的增强，这导致费米能级附近的电子态密度增加。最后，随着压力增加到6.1吉帕及以上，沿c轴的Se - Sn - Se之间的电荷分布逐渐从不对称变为对称。这意味着SnSe结构对称性的增强会导致电荷的对称分布，进而进一步影响Sn - Se键的键合特性。
