## Abstract

Molecular dynamics simulations show that graphite will transform into a superhard phase under cold compression. Recent experiments show that there is a sp
^{3}-rich hexagonal carbon polymorph (a
_{0}=2.496 Å, c
_{0}=4.123Å) with a bulk modulus of 447 GPa and average density about 3.6g/cm
^{3}, restricted to the space group of P-62c (No. 190), but the detailed atomic structure was not obtained [Wang et al., P. Natl. Acad. Sci. 101(38), 13699]. Here we set carbon atoms occupying P-62c 4f Wyckoff positions of P-62c, and calculate the total energy of the different structures changing the internal parameter z by first-principles calculations using geometry optimisation algorithm in CASTEP code, which shows that the stable structures in energy (at local minimum points) are hexagonal carbon (z=1/4) and hexagonal diamond (z=1/16). The calculated mechanical properties and lattice parameters of the structure P-62c 4f (z=1/4) are in good agreement with those of the new hexagonal carbon proposed by Wang et al., which indicates that the atomic structure is a possible candidate.

Original language | English |
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Title of host publication | ISCM II and EPMESC XII - Proc. of the 2nd Int. Symposium on Computational Mechanics and the 12th Int. Conf. on the Enhancement and Promotion of Computational Methods in Engineering and Science |

Pages | 489-493 |

Number of pages | 5 |

Volume | 1233 |

Edition | PART 1 |

DOIs | |

Publication status | Published - 2010 |

Event | 2nd International Symposium on Computational Mechanics, ISCM II, and the 12th International Conference on the Enhancement and Promotion of Computational Methods in Engineering and Science, EPMESC XII - Hong Kong, Macau, China Duration: 30 Nov 2009 → 3 Dec 2009 |

### Conference

Conference | 2nd International Symposium on Computational Mechanics, ISCM II, and the 12th International Conference on the Enhancement and Promotion of Computational Methods in Engineering and Science, EPMESC XII |
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Country | China |

City | Hong Kong, Macau |

Period | 30/11/09 → 3/12/09 |