### Abstract

We calculate the electronic and lattice properties of C_{6}B _{2} (Na_{3}As type crystal structure) using the first-principles molecular dynamics (FPMD) method. C_{6}B_{2} is a hypothetical hexagonal compound, which consists of two B-C layers and two C-C layers. All calculated electronic band structures are metallic. C _{6}B_{2} has unoccupied flat bands close to the Fermi level at the Γ-A line. These flat bands correspond to unoccupied σ-bands of MgB_{2} at the Γ-A line. Displacements of B atoms along a B-C bond split unoccupied flat bands at the Γ-A line into two subbands. A total energy change with displacements of B atoms indicates anharmonicity of a B-C stretching mode. We investigate C_{6}B_{2} under various compression conditions. The change in the electronic band structure under a, b-axis compression (P_{xy}) is small. In contrast, it is quite remarkable under c-axis compression (P_{z}). We find the lattice anomaly of C_{6}B_{2} under a, b-axis compression. This anomaly shows a kind of negative Poisson ratios.

Original language | English |
---|---|

Pages (from-to) | 374-380 |

Number of pages | 7 |

Journal | Physica C: Superconductivity and its Applications |

Volume | 426-431 |

Issue number | I |

DOIs | |

Publication status | Published - Oct 1 2005 |

Externally published | Yes |

### Fingerprint

### Keywords

- CB
- Electronic band structure
- First principles
- Lattice anomaly

### ASJC Scopus subject areas

- Condensed Matter Physics

### Cite this

*Physica C: Superconductivity and its Applications*,

*426-431*(I), 374-380. https://doi.org/10.1016/j.physc.2005.01.031

**First-principles study of C6B2
.** / Kobayashi, Kazuaki; Zenitani, Yuji; Akimitsu, Jun.

Research output: Contribution to journal › Article

*Physica C: Superconductivity and its Applications*, vol. 426-431, no. I, pp. 374-380. https://doi.org/10.1016/j.physc.2005.01.031

}

TY - JOUR

T1 - First-principles study of C6B2

AU - Kobayashi, Kazuaki

AU - Zenitani, Yuji

AU - Akimitsu, Jun

PY - 2005/10/1

Y1 - 2005/10/1

N2 - We calculate the electronic and lattice properties of C6B 2 (Na3As type crystal structure) using the first-principles molecular dynamics (FPMD) method. C6B2 is a hypothetical hexagonal compound, which consists of two B-C layers and two C-C layers. All calculated electronic band structures are metallic. C 6B2 has unoccupied flat bands close to the Fermi level at the Γ-A line. These flat bands correspond to unoccupied σ-bands of MgB2 at the Γ-A line. Displacements of B atoms along a B-C bond split unoccupied flat bands at the Γ-A line into two subbands. A total energy change with displacements of B atoms indicates anharmonicity of a B-C stretching mode. We investigate C6B2 under various compression conditions. The change in the electronic band structure under a, b-axis compression (Pxy) is small. In contrast, it is quite remarkable under c-axis compression (Pz). We find the lattice anomaly of C6B2 under a, b-axis compression. This anomaly shows a kind of negative Poisson ratios.

AB - We calculate the electronic and lattice properties of C6B 2 (Na3As type crystal structure) using the first-principles molecular dynamics (FPMD) method. C6B2 is a hypothetical hexagonal compound, which consists of two B-C layers and two C-C layers. All calculated electronic band structures are metallic. C 6B2 has unoccupied flat bands close to the Fermi level at the Γ-A line. These flat bands correspond to unoccupied σ-bands of MgB2 at the Γ-A line. Displacements of B atoms along a B-C bond split unoccupied flat bands at the Γ-A line into two subbands. A total energy change with displacements of B atoms indicates anharmonicity of a B-C stretching mode. We investigate C6B2 under various compression conditions. The change in the electronic band structure under a, b-axis compression (Pxy) is small. In contrast, it is quite remarkable under c-axis compression (Pz). We find the lattice anomaly of C6B2 under a, b-axis compression. This anomaly shows a kind of negative Poisson ratios.

KW - CB

KW - Electronic band structure

KW - First principles

KW - Lattice anomaly

UR - http://www.scopus.com/inward/record.url?scp=25444439526&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=25444439526&partnerID=8YFLogxK

U2 - 10.1016/j.physc.2005.01.031

DO - 10.1016/j.physc.2005.01.031

M3 - Article

AN - SCOPUS:25444439526

VL - 426-431

SP - 374

EP - 380

JO - Physica C: Superconductivity and its Applications

JF - Physica C: Superconductivity and its Applications

SN - 0921-4534

IS - I

ER -