title: Metastable C-centered orthorhombic Si8 and Ge8.
abstract: A theoretical prediction on the structural stabilities, mechanical properties, and electronic properties of the C-centered orthorhombic (Cco) Si(8) and Ge(8) is presented, inspired by a recently proposed carbon allotrope structure, Cco-C(8). Energetically comparable with previously known metastable phases, Cco-Si(8) and Cco-Ge(8) may be obtained by decompressing the high-pressure β-Sn phases, or by compressing the corresponding nanotubes. The calculated bulk moduli of Cco-Si(8) and Cco-Ge(8) are close to those of the diamond phases. Further study of the electronic properties reveals that the band gaps of Cco-Si(8) and Cco-Ge(8) are tunable with variations in lattice parameters.
authors.affiliation: State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, People's Republic of China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Zhai
authors.forename: Dongli
authors.initials: D
authors.lastname: Yu
authors.forename: Kun
authors.initials: K
authors.lastname: Luo
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Wang
authors.forename: Zhisheng
authors.initials: Z
authors.lastname: Zhao
authors.forename: Julong
authors.initials: J
authors.lastname: He
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Tian
mesh_terms: D003198:Computer Simulation; D055119:Elastic Modulus; D004553:Electric Conductivity; D005857:Germanium / Q000737:chemistry*; D006244:Hardness; D008956:Models, Chemical; D008958:Models, Molecular; D012825:Silicon / Q000737:chemistry*
chemical_list: D005857:Germanium; D012825:Silicon