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[15a-A403-10] Design of a three-dimensional carbon allotrope comprising fused pentagons
Keywords:diamond, material design
A pentagonal covalent network consisting of sp2 and sp3 C atoms were investigated based on the density functional theory. These theoretical investigations clarified that this pentagonal covalent network is a stable three-dimensional carbon allotrope with the Fm3-m space group that possesses a relatively high bulk modulus of 381 GPa together with a negative Poisson's ratio of -0.241. Accordingly, the pentagonal covalent network possesses extremely high Young's and shear moduli of 1692 and 1115 GPa, respectively, surpassing those of the diamond. The electronic structure of the pentagonal network is a semiconductor with an indirect band gap of 2.52 eV between the L and X points for valence and conduction band edges, respectively, with relatively small carrier masses.