可控单键生成和表征的第一性原理研究

A first-principles investigation for bond selective chemical experiments

WilsonHo等人利用扫描隧道显微镜 (STM)针尖对吸附在Ag( 1 1 0 )表面的Fe、Cu原子和CO分子进行操纵 ,并让一个或两个CO分子与金属原子成键。本文使用团簇模型对此体系进行了密度泛函研究 ,得到体系吸附构型 ,模拟其STM图像 ,并计算出了实验测量到的振动频率 ,同时预言了CO在另外四种金属表面的吸附构型和C—O伸缩振动频率。这六种金属可以按照其d轨道是否充满分为两类 。

Fe, Cu atoms and CO molecules were manipulated with a STM tip on a Ag(110) surface, and one or two CO can transfer from the surface and bond with an metal atom in recent experiments (H. L. Lee and W. Ho, Science, 1999, 286, 1719; Phys. Rev. B, 2000, 61, R16347). We performed a first principles investigation for the experiments, using cluster models and the local density approximation. The experimental adsorbed geometries were explained. The structural parameters and binding energies were obtained. The STM topographic images were reproduced well. The experimental vibrational frequencies were achieved accurately by a simple method. The geometries and C O stretch frequencies were predicted for other four metal atoms. The six metal atoms can be divided into two classes due to whether their d orbitals are fully occupied, and each class corresponds to a set of properties. Our methods will be useful to deal with more systems about the bond selective chemistry.