Orthorhombic C10: A new superdense carbon allotrope

By using unbiased crystal structure searching technique combined with first-principles calculations, a new superdense carbon phase C-10 (space group: C222) with a density of 3.55 g/cm(3) (larger than that of diamond (3.50 g/cm(3))) is uncovered. The C-10 phase has a 10-atom unit cell in the full spa bonding network. A systematic theoretical study of the electronic, dynamic, optical, and elastic properties of superdense carbon C-10 was carried out. In addition, we studied the homologous fracture mode by calculating the ideal tensile and shear strength of C-10 phase. It was confirmed that C-10 is a superhard insulator material with HSE06 band gap of 4.60 eV. (C) 2019 Elsevier B.V. All rights reserved.