Molecular Modeling Laboratory, IPCF-CNR, Via Giuseppe Moruzzi 1, Pisa I56124, Italy.
J Chem Phys. 2010 Mar 28;132(12):124703. doi: 10.1063/1.3366689.
A comparison between available experimental information and the predictions of density-functional and density-functional+U approaches is presented for oxide ultrathin films grown on single-crystal metal surfaces. Prototypical examples of monolayer phases of an ionic oxide (ZnO), a late transition metal oxide (NiO), and an early transition metal oxide (TiO(2)) are considered. The aim is to validate the theoretical approaches, focusing on the prediction of structural features and the reproduction of scanning tunneling microscopy images, rationalized in terms of the local density of states of the systems. It is found that it is possible to reasonably estimate the optimal lattice constant of ultrathin supported films and that the inclusion of the Hubbard U term appreciably improves the accuracy of theoretical predictions, especially in the case of nonpolar ultrathin phases of a transition metal oxide. Moreover, the optimal value of U for the oxide layer at the interface with the metal support is found to differ from that appropriate for the bulk oxide, as a consequence of the intermixing of oxide and support electronic states and screening effects.
呈现了可用实验信息与密度泛函和密度泛函+U 方法的预测之间的比较，这些方法用于研究在单晶金属表面生长的氧化物超薄薄膜。考虑了离子氧化物（ZnO）、晚期过渡金属氧化物（NiO）和早期过渡金属氧化物（TiO(2)）单层相的典型例子。目的是验证理论方法，重点是预测结构特征和根据系统的局域态密度来解释扫描隧道显微镜图像。结果发现，合理估计超薄支撑膜的最佳晶格常数是可能的，并且 Hubbard U 项的包含显著提高了理论预测的准确性，特别是在过渡金属氧化物非极性超薄相的情况下。此外，还发现与金属支撑体界面处氧化物层的最佳 U 值不同于适用于体氧化物的 U 值，这是氧化物和支撑体电子态混合以及屏蔽效应的结果。
