Institute of Experimental Physics, University of Wrocław, Plac M. Borna 9, PL-50-204 Wrocław, Poland.
J Phys Condens Matter. 2012 Mar 7;24(9):095003. doi: 10.1088/0953-8984/24/9/095003. Epub 2012 Jan 25.
The structure and electronic properties of different terminations of the α-Fe(2)O(3)(0001) surface were studied with spin-polarized density functional theory (DFT) and the DFT + U method accounting for the effect of strong on-site Coulomb correlations. The results for lattice relaxation, electronic and magnetic properties are presented and discussed. Though the DFT and DFT + U methods provide qualitatively very similar surface geometries they differ very much in the prediction of the electronic and magnetic properties, and the surface energetics of the clean α-Fe(2)O(3)(0001). The most stable single iron terminated (0001) surface and the oxygen-rich termination were chosen to study Au and Pd atom adsorption. The results show that both Au and Pd bind strongly to hematite surfaces and induce large changes in their geometry. The DFT + U bonding is weaker by 0.3-0.6 eV than DFT on the iron terminated surface and about 2 eV stronger on the oxygen terminated one. The binding is stronger for Pd than Au and for both adsorbates is distinctly stronger at the oxygen than at the iron terminated surface. On the iron terminated surface the adsorption binding energy per adatom increases both with Au and Pd coverage, whereas for the oxygen terminated one the opposite trend is observed.
采用自旋极化密度泛函理论（DFT）和考虑强局域库仑相关效应的 DFT + U 方法研究了不同终止的 α-Fe(2)O(3)(0001)表面的结构和电子性质。给出并讨论了晶格弛豫、电子和磁性质的结果。尽管 DFT 和 DFT + U 方法提供了非常相似的表面几何形状，但它们在电子和磁性质以及清洁的 α-Fe(2)O(3)(0001)表面的表面能方面的预测存在很大差异。选择最稳定的单铁终止（0001）表面和富氧终止来研究 Au 和 Pd 原子吸附。结果表明，Au 和 Pd 都强烈地与赤铁矿表面结合，并导致其几何形状发生很大变化。DFT + U 键比 DFT 在铁终止表面上弱 0.3-0.6 eV，在氧终止表面上强约 2 eV。Pd 的结合比 Au 强，对于两种吸附物，在氧终止表面上的结合比在铁终止表面上强得多。在铁终止表面上，每个吸附原子的吸附结合能随 Au 和 Pd 的覆盖度增加而增加，而对于氧终止表面则观察到相反的趋势。
