主讲人简介:
Miguel Castro教授,墨西哥国立自治大学(UNAM)化学学院、物理与理论化学系化学讲座教授,国际量子化学研究的早期开拓者和著名学者,主要研究领域包括过渡金属团簇的电子结构及过渡金属团簇与有机/无机分子(如H2O, CO, O2, NO, N2O等)的相互作用。他在在墨西哥国立自治大学攻读化学专业学士学位(1972-1977)、科学硕士学位(1978-1984)和化学学科哲学博士学位(1986-1991),并在加拿大蒙特利尔大学从事博士后(1991-1994)研究,自1990年起任该校化学学科教授至今,并于1999年先后在西班牙圣地亚哥德孔波斯特拉大学物理系和加拿大蒙特利尔大学化学系担任邀请教授,自1999年起担任国际理论化学物理学会理事。他多年来一直从事量子化学基础理论与应用的研究工作,在国际著名期刊发表论文94篇,出版2本学术专著,1982年以来在ISI Web of Science被引总数超过1850,其H-index为25 (ISI Web of Science),是2012和2013年度 Elsevier排名的墨西哥国立自治大学化学学科被引用最高的作者。他曾获2014年墨西哥化学学会颁发的化学国家奖、获墨西哥国立自治大学颁发的1999年至今的“研究与学术轨迹识别计划”的最高奖、2009年至今的墨西哥国家科研人员系统最高奖,3次担任量子化学领域的重要国际会议主席及多个国家著名大学名誉教授或客座教授。
主持人:苏亚欣 教授
报告摘要:
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.