Atomic and electronic structures of montmorillonite in soft rock |
| |
Authors: | He Man-Chao Fang Zhi-Jie and Zhang Ping |
| |
Institution: | State Key Laboratory of Deep Geomechanics and Underground Engineering, China University of Mining and Technology, Beijing 100083, China; Institute of Applied Physics and Computational Mathematics, Beijing 100088, China |
| |
Abstract: | Montmorillonite is a kind of clay mineral which often causes large
deformation in soft-rock tunnel engineering and thus brings about
safety problems in practice. To deal with these engineering safety
problems, the physical and chemical properties of montmorillonite
should be studied from basic viewpoints. We study the atomic and
electronic structures of montmorillonite by using density-functional
theory within the local-density approximation (LDA). The results of
calculation show that Al--O bond lengths are longer than Si--O bond
lengths. It is found that both the valence band maximum (VBM) and
the conduction band minimum (CBM) of montmorillonite are at point
${\it\Gamma}$, and the calculated direct band gap of montmorillonite
is 5.35~eV. We show that the chemical bonding between cations and
oxygen anions in montmorillonite is mainly ionic, accompanied as
well by a minor covalent component. It is pointed out that the VBM
and CBM of montmorillonite consist of oxygen 2p and cation s states,
respectively. Our calculated results help to understand the chemical
and physical properties of montmorillonite, and are expected to be a
guide for solving the problem of large deformation of soft-rock
tunnels. |
| |
Keywords: | montmorillonite electronic
structure first-principles method |
本文献已被 维普 等数据库收录! |
| 点击此处可从《中国物理 B》浏览原始摘要信息 |
| 点击此处可从《中国物理 B》下载免费的PDF全文 |
|