【大学频道】中国科学院大学卡弗里理论科学研究所呈献 | 杜克大学杨伟涛教授

更多精彩视频登陆网站

www.koushare.com

图 | 杨伟涛教授

题   目：Analysis and Elimination of the Delocalization and Static/Strong Correlation Error in Density Functional Approximations

报告人：杨伟涛

单   位：Duke University

时   间：2019-05-30

地   点：中国科学院大学

扫码观看精彩报告视频

报告摘要

The perspectives of fractional charges and fractional spins provide a clear analysis of the errors of commonly used density functional approximations (DFAs). These errors, the delocalization and static correlation error, of popular DFAs lead to diversified problems in present-day density functional theory calculations. For achieving a universal elimination of these two errors. we develop a localized orbital scaling correction (LOSC) framework: it accurately characterizes the distributions of global and local fractional electrons and spins, and is thus capable of correcting system energy, energy derivative and electron density in a self-consistent and size-consistent manner. Our approach introduces the explicit derivative discontinuity and largely restores the flat-plane behavior of electronic energy at fractional charges and fractional spins. The LOSC-DFAs lead to systematically improved results, including the dissociation of ionic species, single bonds, multiple bonds without breaking the space or spin symmetry, the band gaps of molecules and polymer chains, the energy and density changes upon electron addition and removal, and photoemission spectra.

We further carried the comparison of experimental quasiparticle energies for many finite systems with calculations from the GW Green function and the localized orbitals scaling correction (LOSC). Extensive results with over 40 systems clearly show that LOSC orbital energies achieve slightly better accuracy than the GW calculations with little dependence on the semilocal DFA, supporting the use of LOSC DFA orbital energies to predict quasiparticle energies. This also leads to the QE-DFT (quasiparticle energies from DFT) approach: the calculations of excitation energies of the N-electron systems from the ground state DFA calculations of the (N-1)-electron systems. Results show good performance with accuracy similar to TDDFT and the delta SCF approach for valence excitations with commonly used DFAs with or without LOSC. For charge transfer and Rydberg states. good accugood accuracy was obtained only with the use of LOSC DFA. The QE-DFT method has been further developed to describe excited-state potential energy surfaces (PESs), conical intersections, and the analytical gradients of excited-state PESs.

个人简介

Prof. Yang, the Philip Handler Professor of Chemistry, is developing methods for quantum mechanical calculations of large systems and carrying out quantum mechanical simulations of biological systems and nanostructures. Education: Ph.D., University of North Carolina at Chapel Hill (1986). B.S., Peking University (China) (1982). Reacher: His group has developed the linear scaling methods for electronic structure calculations and more recently the QM/MM methods for simulations of chemical reactions in enzymes.

—— ——往期精彩回顾—— ——

END

扫描二维码，关注微信公众号

戳这里，观看精彩视频哟！