The family of monolayered Si₂BN structures constitute a new class of 2D materials exhibiting metallic character with remarkable stability. Topologically, these structures are very similar to graphene, forming a slightly distorted honeycomb lattice generated by a union of two basic motifs with AA and AB stacking. In the present work we study in detail the structural and electronic properties of these structures in order to understand the factors which are responsible for their structural differences as well as those which are responsible for their metallic behavior and bonding. Their high temperature stability is demonstrated by the calculations of finite temperature phonon modes which show no negative contributions up to and beyond 1000K. Presence of the negative thermal expansion coefficient, a common feature of one-atom thick 2D structures, is also seen. Comparison of the two motifs reveal the main structural differences to be the differences in their bond angles, which are affected by the third nearest neighbor interactions of cis–trans type. On the other hand, the electronic properties of these two structures are very similar, including the charge transfers occurring between orbitals and between atoms. Their metallicity is mainly due to the p _z orbitals of Si with a minor contribution from the p _z orbitals of B, while the contribution from the p _z orbitals of N atoms is negligible. There is almost no contributions from the N p _z electrons to the energy states near the Fermi level, and they form a band well below it. I.e., the p _z electrons of N are localized mostly at the N atoms and therefore cannot be considered as mobile electrons of the p _z cloud. Moreover, we show that due to the relative positions in the energy axis of the atomic energies of the p _z orbitals of B, N and Si atoms, the density of states (DOS) of Si₂BN can be considered qualitatively as a combination of the DOS of planar hexagonal BN (h-BN) and hypothetically planar silicene (ph-Si). As a result, the Si₂BN behaves electronically at the Fermi level as slightly perturbed ph-Si, having very similar electronic properties as silicene, but with the advantage of having kinetic stability in planar form. As for the bonding, the Si–Si bonds are covalent, while the π back donation mechanism occurs for the B–N bonding, in accordance with the B–N bonding in h-BN.

单层Si _{2 族}BN 结构构成了一类新的二维材料，具有显着稳定性的金属特性。从拓扑结构上讲，这些结构与石墨烯非常相似，形成由两个基本图案与 AA 和 AB 堆叠结合生成的略微扭曲的蜂窝晶格。在目前的工作中，我们详细研究了这些结构的结构和电子特性，以了解导致其结构差异的因素以及导致其金属行为和键合的因素。它们的高温稳定性通过有限温度声子模式的计算得到证明，这些模式在 1000K 和 1000K 以上没有负贡献。还可以看到负热膨胀系数的存在，这是单原子厚 2D 结构的一个共同特征。顺式-反式。另一方面，这两种结构的电子特性非常相似，包括轨道之间和原子之间发生的电荷转移。他们的金属丰度是主要是由于p _Ž的Si的与来自次要贡献轨道p _ž B的轨道，而来自的贡献p _Ž N原子的轨道是可忽略的。N p _z电子对费米能级附近的能态几乎没有贡献，并且它们形成远低于该能级的能带。即p _z N 的电子主要集中在 N 原子上，因此不能被视为p _z云的移动电子。此外，我们表明，由于B、N 和 Si 原子的p _z轨道的原子能在能量轴上的相对位置，Si ₂ BN的态密度 (DOS)可以定性地视为平面六方氮化硼 (h-BN) 和假设平面硅烯 (ph-Si) 的 DOS。因此，Si ₂ BN 在费米能级上表现为轻微扰动的 ph-Si，具有与硅烯非常相似的电子特性，但具有在平面形式下具有动力学稳定性的优势。至于键合，Si-Si 键是共价键，而 根据 h-BN 中的 B-N 键，B-N 键发生π回馈机制。