论文标题
Quasi One维weyl手性化合物（Tase $ _4 $）$ _ 2 $ i的低温电荷密度波阶段的第一原理研究
First-principles study of the low-temperature charge density wave phase in the quasi-one-dimensional Weyl chiral compound (TaSe$_4$)$_2$I
论文作者
论文摘要
使用{\ it Ab intib}密度函数理论，我们研究了准二维的晶格相变（tase $ _4 $）$ _ 2 $ i。在未变形的状态下，强烈的各向异性半分带结构呈现两个非等效的Weyl点。在先前的努力中，提出了两种可能的TA四聚体模式与低温结构有关。我们的声子计算表明，正交$ f222 $ cdw-i相是该准二维系统最有可能的基础状态。此外，根据声子分散频谱，单斜$ C2 $ CDW-II相也可能是稳定的。由于这两个阶段在我们的DFT计算中具有非常相似的能量，因此这两个TATAMERIZARIZE扭曲都可能在低温下竞争或共存。半学到绝缘体的转变是由支持PEIERLS方案的Fermi-Surface驱动的不稳定性引起的，该场景影响了$ t _ {\ rm cdw} $高于$ t _ {\ rm cdw} $的Weyl Physics。此外，自旋轨道耦合在绝缘CDW相中会产生类似Rashba的带状带分裂。
Using {\it ab initio} density functional theory, we study the lattice phase transition of quasi-one-dimensional (TaSe$_4$)$_2$I. In the undistorted state, the strongly anisotropic semimetal band structure presents two non-equivalent Weyl points. In previous efforts, two possible Ta-tetramerization patterns were proposed to be associated with the low-temperature structure. Our phonon calculations indicate that the orthorhombic $F222$ CDW-I phase is the most likely ground state for this quasi-one-dimensional system. In addition, the monoclinic $C2$ CDW-II phase may also be stable according to the phonon dispersion spectrum. Since these two phases have very similar energies in our DFT calculations, both these Ta-tetramerization distortions likely compete or coexist at low temperatures. The semimetal to insulator transition is induced by a Fermi-surface-driven instability that supports the Peierls scenario, which affects the Weyl physics developed above $T_{\rm CDW}$. Furthermore, the spin-orbit coupling generates Rashba-like band splittings in the insulating CDW phases.
