title: Three dimensional carbon-nanotube polymers.
abstract: Eight fascinating sp(2)- and sp(3)-hybridized carbon allotropes have been uncovered using a newly developed ab initio particle-swarm optimization methodology for crystal structure prediction. These crystalline allotropes can be viewed respectively as three-dimensional (3D) polymers of (4,0), (5,0), (7,0), (8,0), (9,0), (3,3), (4,4), and (6,6) carbon nanotubes, termed 3D-(n, 0) or 3D-(n, n) carbons. The ground-state energy calculations show that the carbons all have lower energies than C(60) fullerene, and some are energetically more stable than the van der Waals packing configurations of their nanotube parents. Owing to their unique configurations, they have distinctive electronic properties, high Young's moduli, high tensile strength, ultrahigh hardness, good ductility, and low density, and may be potentially applied to a variety of needs.
authors.affiliation: State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.
authors.forename: Zhisheng
authors.initials: Z
authors.lastname: Zhao
authors.forename: Bo
authors.initials: B
authors.lastname: Xu
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Wang
authors.forename: Xiang-Feng
authors.initials: XF
authors.lastname: Zhou
authors.forename: Julong
authors.initials: J
authors.lastname: He
authors.forename: Zhongyuan
authors.initials: Z
authors.lastname: Liu
authors.forename: Hui-Tian
authors.initials: HT
authors.lastname: Wang
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Tian