发表机构
University of Missouri（密苏里大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究过渡金属二碲化物五边形单层，通过第一性原理计算，构建结构插值表明半金属到半导体转变在中间结构阈值后发生，能隙打开与Te-Te二聚体形成有关，且五边形相有对称保护二维狄拉克态，确立其为新型二维半导体。
AI 中文摘要
最近合成的五边形 PdTe₂ 单层激发了对过渡金属二碲化物更广泛的研究兴趣，其电子相受对称性和结构重构支配。过渡金属二碲化物的五边形相由于较低的晶体对称性，表现出与其六边形对应物截然不同的电子特性。我们使用第一性原理计算研究了六边形和五边形多晶型中的单层 XTe₂（X = Pd、Pt、Ni）。通过在六边形和五边形相之间构建连续的结构插值，我们表明半金属（六边形）到半导体（五边形）的转变仅在中间结构阈值之后发生，而不是在对称性降低开始时。能隙的打开与 Te-Te 二聚体的形成相吻合，这驱动了 Te p 态的键合 - 反键分裂并重组了能带边缘。此外，五边形相的非对称对称性在布里渊区边界强制能带简并，导致对称保护的二维狄拉克态。这些结果将五边形 XTe₂ 单层确立为一类新型的二维半导体，其中对称性约束和局部键合共同塑造了非常规的半导体电子结构。
英文摘要
The recent synthesis of pentagonal PdTe$_2$ monolayer motivates broader research interests in transition-metal ditellurides whose electronic phases are governed by symmetry and structural reconstruction. The pentagonal phase of transition-metal ditellurides exhibits electronic properties that are dramatically different from those of its hexagonal counterpart due to its lower crystalline symmetry. Using first-principles calculations, we study monolayer $X$Te$_2$ ($X=\mathrm{Pd},\mathrm{Pt},\mathrm{Ni}$) in both hexagonal and pentagonal polymorphs. By constructing a continuous structural interpolation between the hexagonal and pentagonal phases, we show that the semimetal (hex)-to-semiconductor (penta) transition occurs only after an intermediate structural threshold rather than at the onset of symmetry reduction. The gap opening coincides with the formation of Te--Te dimers, which drive the bonding--antibonding splitting of the Te $p$ states and reorganize the band edges. In addition, the nonsymmorphic symmetry of the pentagonal phase enforces band degeneracies at the Brillouin-zone boundary, leading to symmetry-protected two-dimensional (2D) Dirac states. These results establish pentagonal $X$Te$_2$ monolayers as a new class of 2D semiconductors in which symmetry constraints and local bonding collectively shape the unconventional semiconducting electronic structure.
Comments30 pages, 5 figures, 2 tables; 19 pages of supplementary information. Published in Materials Today Physics
Journal refMaterials Today Physics 68 (2026) 102238
DOI：10.1016/j.mtphys.2026.102238
