Research On Novel Carbon Allotropes Based On First Principle Calculation

The carbon element and its allotropes are one of the most important elements in the material world,has a pivotal impact on human society.Due to the continuous improvement and rapid development of computer performance and first-principles calculation methods over the years,it has been possible to predict theoretically the ground state and metastable structure of materials based only on a given chemical composition and external conditions(such as pressure).Theoretical simulation calculation has the characteristics of high efficiency and low cost compared with trial-based exploration in experiment.In this paper,using the crystal structure prediction software CALYPSO based on Particle swarm optimization,two new carbon structures,C72 and oC16,are reported.The structure,mechanical and electronic properties of C72 and oC16 have been studied by using the first-principles calculation method.It was found that the C72 structure is composed of all sp2 hybrid bonds,which is a direct band gap semiconductor material with lower energy(only 0.16 eV/atom higher than diamond)and low density.The oC16 structure is composed of all sp3 hybrid bonds,which is a porous and superhard insulator material.In addition,this paper combines first-principles calculations and quasi-harmonic Debye model to study the structure,elastic properties,elastic anisotropy,electronic structure and thermodynamic properties of another new carbon material TE-C36 under high pressure.The results show that pressure has a significant effect on the physical properties of TE-C36.The elastic constant,elastic modulus,and Poisson's ratio of TE-C36 under pressure increase with increasing pressure,while the hardness and band gap width show the opposite change.The studies presented in this paper will help to guide experimental synthesis and application of these new carbon materials in the future.Figure[32]reference[104].