题目

Atomic Scale Simulations of Materials and Chemicals Based on Electronic Structure and Rate Theory

报告人

Prof. Hannes Jónsson

University of Iceland　　　　　　　　　　　　　　 

时间

2016年5月24日（星期二）上午10：00

地点

微尺度国家实验室9004会议室

Prof. Jónsson received his B.S. degree in Chemistry from the University of Iceland in 1980, and a Ph.D.  at the University of California San Diego in 1985. After a two year post-doc at Stanford, he became an assistant, then associate and finally full professor at University of Washington in Seattle. In 2005, he moved back to Iceland to become professor at the University of Iceland. He has been a visiting professor at the Technical University of Denmark and at SLAC/Stanford. He is currently a Finland Distinguished Professor at Aalto University in Finland. Prof. Jónsson has developed several methods for calculating rates of slow transitions, such as chemical reactions and diffusion including the well known CI-NEB method.　

报告摘要

The combination of density functional theory (DFT) for describing electronic structure and rate theory for obtaining the mechanism and rate of atomic scale transitions provides a powerful tool that can help with interpretation of experimental measurements and even prediction of the properties of new materials and chemicals.  Several applications of this methodology in the study of surfaces of solids and nanoclusters will be given, for example: (1) re-entrant mechanism for thermal desorption of H₂ from a Pt surface, (2) structural changes and catalysis of Au nanoclusters, and (3) rate of formation of various hydrocarbons and alcohols in CO₂ electrochemical reduction. It is even possible to simulate long time scale evolution in atomic systems as a sequence of rare events by finding transition states without imposing a preconceived notion of the possible final states. The adaptive kinetic Monte Carlo method is such a long time scale simulation tool which has so far mainly been used in the context of empirical potentials and harmonic transitions state theory, but as computational power increases the use of DFT in this context becomes viable as well as an extension to full transition state theory plus dynamical corrections. The standard implementation of DFT, the Kohn-Sham methodology does, however, have practical limitations resulting in self-interaction error that can lead to qualitatively incorrect results. The application of explicit self-interaction correction can greatly improve the accuracy especially for systems where a delicate balance between localized and delocalized electronic states exists and where the long range tail of the effective potential of an electron is of importance.