First-principles study of C6B2

Kazuaki Kobayashi; Yuji Zenitani; Jun Akimitsu

doi:10.1016/j.physc.2005.01.031

First-principles study of C₆B₂

Kazuaki Kobayashi, Yuji Zenitani, Jun Akimitsu

Research output: Contribution to journal › Conference article › peer-review

3 Citations (Scopus)

Abstract

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 (P_xy) is small. In contrast, it is quite remarkable under c-axis compression (P_z). We find the lattice anomaly of C₆B₂ 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	https://doi.org/10.1016/j.physc.2005.01.031
Publication status	Published - Oct 1 2005
Externally published	Yes
Event	Proceedings of the 17th International Symposium on Superconductivity (ISS 2004) Advances in Supeconductivity - Duration: Nov 23 2004 → Nov 25 2004

Keywords

CB
Electronic band structure
First principles
Lattice anomaly

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Energy Engineering and Power Technology
Electrical and Electronic Engineering

Access to Document

10.1016/j.physc.2005.01.031

Cite this

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title = "First-principles study of C6B2",

abstract = "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.",

keywords = "CB, Electronic band structure, First principles, Lattice anomaly",

author = "Kazuaki Kobayashi and Yuji Zenitani and Jun Akimitsu",

year = "2005",

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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.

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KW - First principles

KW - Lattice anomaly

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