I4/mcm-Si48: An Ideal Topological Nodal-Line Semimetal

Topological semimetals (TSMs) have attracted much attention
due
to their exotic physical properties and great application potential.
Silicon-based TSMs are of particularly importance because of their
abundance, nontoxicity, and natural compatibility with the current
semiconductor industry. In this work, an ideal low-energy topological
nodal-line semimetal (TNLSM) silicon (I4/mcm-Si48) with a clean band crossing at the Fermi
level is screened from thousands of silicon allotropes by general
and transferable tight-binding and DFT calculations. The results of
formation energy, phonon dispersion, ab initio molecular dynamics,
and elastic constants show that I4/mcm-Si48 possesses good stability and is more stable than
several synthesized silicon structures. Furthermore, I4/mcm-Si48 exhibits exotic photoelectric
properties, and the Dirac fermions with high Fermi velocity (3.4–4.36
× 105 m/s) can be excited by low-energy photons. Our
study provides a promising topological nodal-line semimetal for fundamental
research and potential applications in semiconductor-compatible high-speed
photoelectric devices.

拓扑半金属（TSMs）因其独特的物理属性和巨大的应用潜力而备受关注。基于硅的TSMs尤为重要，这是因为硅的丰富性、非毒性以及与现有半导体工业的天然兼容性。在本研究中，通过通用的、可转移的紧束缚和DFT计算，从数千种硅同素异形体中筛选出了一种理想低能拓扑节点线半金属（TNLSM）硅（I4/mcm-Si48），其费米能级处具有清晰的能带交叉。形成能、声子色散、原位分子动力学模拟以及弹性常数的计算结果表明，I4/mcm-Si48具有良好的稳定性，且比几种已合成的硅结构更稳定。此外，I4/mcm-Si48展现出异质的光电性质，具有高费米速度（3.4–4.36 × 105 m/s）的狄拉克费米子可以通过低能光子被激发。本研究为基本研究以及半导体兼容的高速光电器件的潜在应用提供了一种有前景的拓扑节点线半金属。