TKX-50高压下结构、力学性质及电子特性的第一性原理研究

Structural,Mechanical and Electronic Properties of Dihydroxylammonium 5,5'-Bistetrazole-1,1'-diolate(TKX-50) under High Pressures: A First-principles Study

采用色散校正密度泛函(DFT-D)方法模拟了1,1'–二羟基-5,5'-联四唑二羟胺盐(T KX-50)晶体在高压下的结构、力学性质及电子特性,得到了T KX-50晶体的弹性常数、体弹模量以及高压下状态方程、能带带隙的演变。用Hirshfeld面及2D指纹图分析了高压下分子间的相互作用的变化规律。模拟的结构与文献报道的实验数据一致。晶格的压缩性存在较大的各向异性,b轴最容易被压缩,三个轴向的可压缩性大小顺序为b>c>a。通过弹性常数计算获得了其常压下的硬度常数大小顺序为C_(33)(61.9 GPa)>C_(11)(58.1 GPa)>C_(22)(36.9 GPa)。T KX-50的带隙在零压下是直接带隙,在50 GPa及更高压力下为间接带隙,带隙随着压力增加而减小,预示T KX-50可能在压力下撞击感度增大。

The structures and mechanical and electronic properties of dihydroxylammonium 5,5＇-Bistetrazole-1,1＇-diolate（TKX-50） were examined over a pressure range to clarify its structural and chemical stability at high pressures with a first-principles method based on density functional theory using PBE functional plus vdW corrections（DFT-D）. The intermolecular interactions under high pressures were analyzed with the Hirshfeld surfaces and 2D fingerprint plots to clarify its change trend. The calculated lattice constants, axial compressibility, and equation of state are in good accordance with the available experimental results. For the first time, we predict the elastic constants of TKX-50 using a first-principles method. The predicted stiffness constants are ordered as C33（61.9 GPa〉C11（58.1 GPa）〉C22（36.9 GPa）. The electronic energy band structures show that the band gap changes from a direct one （B-B） at 0 GPa to an indirect one at 50 GPa. The band gap at 100 GPa is also indirect （from G to B）. The band gap decreases with respect to an increase in pressure, implying that the impact sensitivity increases with compression.