We applied the hydrostatic and uniaxial pressure respectively to cubic PbS based on the plane-wave pseudo-potential density functional theory. The calculated results indicate that the band gap of PbS closes and reopens under hydrostatic pressure like a topological crystalline insulator, although it isn't a topological crystalline insulator because the pressure induced phase transition will occur when the hydrostatic pressure increases to about 2.2GPa in fact. In addition, we find that, unlike the case of hydrostatic pressing, when the uniaxial pressure is applied along [001] direction, PbS is converted from a direct band gap semiconductor to an indirect band gap semiconductors.

中文翻译：

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压力引起的PbS带隙变化的研究

基于平面波伪势密度泛函理论，我们分别对立方PbS施加了静水压力和单轴压力。计算结果表明，PbS的带隙在静水压力下像拓扑晶体绝缘子一样闭合和重新打开，尽管它不是拓扑晶体绝缘子，因为当静水压力实际上增加到约2.2GPa时会发生压力诱导的相变。 。另外，我们发现，与流体静压的情况不同，当沿[001]方向施加单轴压力时，PbS从直接带隙半导体转换为间接带隙半导体。