The role of isotropic and anisotropic Hubbard corrections for the magnetic ordering and absolute band alignment of hematite a-Fe2O3(0001) surfaces
The role of isotropic and anisotropic Hubbard corrections for the magnetic ordering and absolute band alignment of hematite a-Fe2O3(0001) surfaces
复制标题
各向同性和各向异性哈伯德校正对赤铁矿 a-Fe2O3(0001) 表面磁有序和绝对能带排列的作用
DOI：
10.1016/j.pnsc.2019.05.010
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Bandaru S
中科院分区：
文献类型：
--
作者：
Bandaru S
对块状赤铁矿（α-Fe 2 O3）进行了各向同性（+U）和各向异性[+（U-J）]修正的密度泛函理论研究，并通过厚度从12层增加到36层的板模拟了其（0001）表面的几个竞争终端。尽管存在微小的定量差异，但无论使用何种U或（U-J）校正，均未对所研究的体相α-Fe 2 O3和最低能量α-Fe 2 O3（0001）表面的模拟结果产生定性影响，而与所使用的板坯厚度无关。弛豫后的板片中保留了有利于体相α-Fe 2 O3反铁磁有序的能量，最大的表面诱导效应仅限于板片中最外层的三个Fe层。混合的O-和Fe-终端被发现是积极的青睐和绝缘。相反，完全O-或Fe-终止的表面被计算为在能量上不利的和金属的。最后，针对提高α-Fe_2O_3（0001）表面光电极水分解活性的挑战，分析和讨论了Fe-或O-封端对α-Fe_2O_3（0001）表面半导体或金属性质以及绝对能带排列的作用。
An isotropic (+U) and anisotropic [+(U−J)] corrected Density Functional Theory study for bulk hematite (α-Fe2O3) was carried out, and several competing terminations of its (0001) surface modeled via slabs of increasing thickness from twelve to thirty-six Fe-layers. In spite of small quantitative differences, the use of either U or (U-J) corrections showed not to qualitatively affect the results of the simulations both for bulk α-Fe2O3and the lowest-energy α-Fe2O3(0001) surface studied, regardless of the thickness of the slab used. The energy favored antiferromagnetic ordering of bulk α-Fe2O3was preserved in the relaxed slabs, with the largest surface-induced effects limited to the outermost three Fe-layers in the slabs. Mixed O- and Fe-terminations were found to be energetically favored and insulating. Conversely, fully O- or Fe-terminated surfaces were calculated to be energetically disfavored and metallic. Finally, the role of Fe- or O- termination for the semiconducting or metallic nature as well as absolute band alignment of α-Fe2O3(0001) surfaces was analyzed and discussed with respect to the challenges in enhancing the activity of α-Fe2O3samples as photo-electrode for water splitting.