title: Ab initio structure determination of n-diamond.
abstract: A systematic computational study on the crystal structure of n-diamond has been performed using first-principle methods. A novel carbon allotrope with hexagonal symmetry R32 space group has been predicted. We name it as HR-carbon. HR-carbon composed of lonsdaleite layers and unique C3 isosceles triangle rings, is stable over graphite phase above 14.2 GPa. The simulated x-ray diffraction pattern, Raman, and energy-loss near-edge spectrum can match the experimental results very well, indicating that HR-carbon is a likely candidate structure for n-diamond. HR-carbon has an incompressible atomic arrangement because of unique C3 isosceles triangle rings. The hardness and bulk modulus of HR-carbon are calculated to be 80 GPa and 427 GPa, respectively, which are comparable to those of diamond. C3 isosceles triangle rings are very important for the stability and hardness of HR-carbon.
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.|State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
authors: Da
authors: D
authors: Li
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.
authors: Fubo
authors: F
authors: Tian
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.
authors: Binhua
authors: B
authors: Chu
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.
authors: Defang
authors: D
authors: Duan
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.
authors: Xiaojing
authors: X
authors: Sha
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.
authors: Yunzhou
authors: Y
authors: Lv
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.
authors: Huadi
authors: H
authors: Zhang
authors: State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
authors: Nan
authors: N
authors: Lu
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.
authors: Bingbing
authors: B
authors: Liu
authors: State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P. R. China.
authors: Tian
authors: T
authors: Cui