Dirac Semimetal Protected by Nonsymmorphic Mirror Symmetries in TPH‐Graphene

Abstract

Dirac cones in 2D carbon allotropes are generally protected by symmorphic symmetry operations. Herein, it is proposed that TPH-graphene has Dirac cones protected by nonsymmorphic mirror symmetries. This monolayer is composed of tetragonal, pentagonal, and heptagonal carbon rings and exhibits not only good mechanical and dynamic stability but also high energetic stability. The structure has anisotropic mechanical properties, and its Young's modulus is close to that of graphene, up to 291 N m À1 . The Dirac points on high-symmetry lines ΓÀX and XÀS are protected by the nonsymmorphic mirror operations fm 010 j0, 1=2, 0g and fm 100 j0, 1=2, 0g, respectively. The edge states obtained from semi-infinite structures confirm the nontrivial topological nature of these cones. The work reveals that TPH-graphene is an excellent candidate to study nonsymmorphicsymmetry-protected Dirac cones in 2D carbon materials.

Nonsymmorphic P21/m‐MoTe2: Novel 2D Topological Materials

“…We can find that there are two Dirac cones on high-symmetry line Γ-Y and the edge states clearly can be seen. The edge states are similar to that of other 2D Dirac semimetallic materials when SOC is not considered, such as 1T'-WTe 2 , [10] TPH-graphene, [63] ZrOH, [64] and borophene. [65] The 3D energy bands show that Dirac cone only exists on Γ-Y and there is no Dirac cone along the path of Γ-X.…”

LC567: a new 2D semimetallic carbon allotrope as a promising anode material for lithium-ion batteries

“…It can be shown that, despite having greater energy than graphene (À9.225 eV per atom). It is substantially lower than many other 2D carbon allotropes proposed in theory, [24][25][26][27][28][29][30] which illustrates that the experimental synthesis of this structure has a great possibility.…”

Adsorption and Migration of a Single Lithium on Tetra‐Penta‐Hepta‐Graphene Nanoribbon: a Density Functional Theory Approach

“…The stability of the TPH‐graphene and some of the graphene allotropes is briefly discussed in the recent literature. [ 40 ] The stability is in the order of graphene [−9.22 eV/atom], PAI‐graphene (5–6–7 carbon polygons) [−9.08 eV/atom], TPH‐graphene [−8.83 eV/atom], cp‐graphyne (5‐acetylenic‐type linker) [−8.534 eV/atom], and γ‐graphdiyne [−8.462 eV/atom]. It indicates that the TPH‐graphene shows reasonable stability.…”

“…The stability of the TPH-graphene and some of the graphene allotropes is briefly discussed in the recent literature. [40] The stability is in the order of graphene [À9.…”