新的三维和二维八碳C8和等电子B4N4具有独特的机械和磁性。第一性原理识别
New 3D and 2D Octacarbon C8 and isoelectronic B4N4 having peculiar mechanic and magnetic properties. First-principles identifications
摘要：
基于密度泛函理论计算了八碳原子C8三维和二维化学体系的结合能、能体状态方程、电子局域化ELF图、弹性常数和能带结构.具体地，四方晶系C8被鉴定为具有接近于实验鉴定的立方晶系Ia-3C 8的硬度的粘性;两者都表现出与金刚石相当的硬度。此外，等电子和同构的B4 N4的计算具有略低的硬度，由于离子共价B-N键和带隙具有相同的大小作为金刚石。另一方面，2D-C8被提出具有互穿的两个碳六边形子结构，从能量计算中确定为在铁磁基态中稳定。临界压力为崩溃的磁化PC=12 GPa让指定一个软铁磁行为类似因瓦合金。电子能带结构分析确定了区分磁性碳亚结构（C1）和磁性半导体蜂窝状C26层的特定带。一旦这种多层碳2D化合物作为独立的或在选定的衬底上作为薄或厚膜生长，这些观察就可以提出自旋化学观点
英文摘要：
Cohesive energies, energy-volume equations of states EOS, electron localization ELF maps, elastic constants, and band structures are reported for original octacarbon C8 three dimensional 3D and two-dimensional 2D chemical systems based on density functional theory calculations. Specifically, tetragonal C8 is identified cohesive with hardness close to experimentally identified cubic Ia-3 C8; both exhibiting comparable hardness to diamond. Also, isoelectronic and isostructural B4N4 is calculated with a slightly lower hardness due to the ionocovalent B-N bonding and a bandgap with the same magnitude as Diamond. 2D-C8 on the other side is proposed with interpenetrating two carbon hexagonal substructures, identified from energy calculations as stable in a ferromagnetic ground state. Critical pressure for the collapse of magnetization PC=12 GPa let assign a soft ferromagnetic behavior alike Invar alloys. Electronic band structures analyses identify specific bands differentiating magnetic carbon substructure (C1) from nonmagnetic semi-conducting honeycomb-like C26 layers. These observations let propose spin chemistry perspectives once such multilayered carbon 2D compounds are grown as stand-alone or on selected substrates as thin or thick films
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