作者：Surajit Basak Aksel Kobiałka Andrzej Ptok
化学式为Ni$_{3}$Pb$_{2}$S$_{2*$，R$\bar{3}$对称的闪长岩，含有过渡金属原子形成的kagome亚晶格。最近的实验结果证实了成功合成具有相同结构的Pd$_{3}$Pb$_{2}Ch_{2}$（$Ch$=S，Se）的可能性。本文从理论上研究了这类化合物的动力学财产。此外，我们还研究了用闪长岩结构实现Pt$_{3}$Pb$_{2}Ch_{2}$的可能性。我们证明了Pd$_{3}$Pb$_{2}${it Ch}$_{2*$和Pt$_{3’$Pb$_{2}$S$_{2’$是稳定的，具有R$\bar{3}$m对称性。在Pt$_{3}$Pb$_{2}$S$_{2*$的情况下，存在一个软模式，它是从R$\bar{3}$对称到R$\bar{3}$c对称的结构相变的来源，与kagome子晶格内的畸变有关。我们讨论了在高频模式下体声子色散中实现的声子节点线。我们证明了闪长岩结构可以承载声子表面态，具有很强的依赖性
Shandite with Ni$_{3}$Pb$_{2}$S$_{2}$ chemical formula and R$\bar{3}$m symmetry, contains the kagome sublattice formed by the transition metal atoms. Recent experimental results confirmed the possibility of successfully synthesizing Pd$_{3}$Pb$_{2}Ch_{2}$ ($Ch$=S,Se) with the same structure. In this paper, we theoretically investigate the dynamical properties of such compounds. Furthermore, we study the possibility of realizing Pt$_{3}$Pb$_{2}Ch_{2}$ with the shandite structure. We show that the Pd$_{3}$Pb$_{2}${\it Ch}$_{2}$ and Pt$_{3}$Pb$_{2}$S$_{2}$ are stable with R$\bar{3}$m symmetry. In the case of Pt$_{3}$Pb$_{2}$S$_{2}$, there is a soft mode, which is the source of the structural phase transition from R$\bar{3}$m to R$\bar{3}$c symmetry, related to the distortion within the kagome sublattice. We discuss realized phonon nodal lines in the bulk phonon dispersions in upper frequency modes. We show that the shandite structure can host the phonon surface states, with strong dependence by the surface kind. Additionally, chiral phonons with circular motion of the Pb atoms around the equilibrium position are realized.
论文链接：http://arxiv.org/pdf/2303.13328v1
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