Magnetic Transition Metal Clusters and Their Interaction with Molecules (磁性过渡金属团簇及其分子的相互作用的量子化学研究)
发布人: 杨小明   发布时间: 2015-10-09    浏览次数:

报告人:Miguel Castro教授

Departamento de Física y Química Teórica, DEPg. Facultad de Química, Universidad Nacional Autónoma de México, México D. F., C. P. 04510, México.

题目Magnetic Transition Metal Clusters and Their Interaction with Molecules   (磁性过渡金属团簇及其分子的相互作用的量子化学研究)

摘要:The lowest energy states of small clusters of titanium, Tin (n ≤ 13), and iron, Fen  (n ≤ 13), atoms were determined by means of all-electrons density  functional theory calculations. Assignment of the ground state for each  cluster was allowed through a comparison of the density of states (DOS)  with the experimental photoelectron spectra (PES) of the anions. The  results indicate the appearance of small magnetic moments (μB) for Tin; reaching rapidly a value of a null μB for Ti13. On the other hand, high magnetic moments, bigger than that of the bulk (2.2 μB for Fe(bcc)) were found on Fen clusters in the size range studied. Indeed, Fen  exhibits superparamagnetism, even for clusters containing hundred of  atoms. Addition of benzene molecules quenches markedly the magnetic  moment of the Fen clusters. Moreover, the ionization energies (IE) of the Fen–(benzene)m systems decrease  notoriously as “m” increases, reaching IEs even smaller than those of  the alkaline atoms. The electron affinity increases as more benzene  molecules are added on the Fen–(benzene)m systems.  These behaviors are accounted by delocalization effects of the valence  electrons through the network of metal–metal and metal–ligand bonds. The  ability of the Fen particles to activate small molecules, such as propane (C3H8) and methane (CH4) will be discussed.

时间: 2015年10月30日(周五),9:30~11:00