报 告 一：室温动态析出强化铝合金和利用“遗传算法”设计低合金超高强马氏体时效钢
主讲嘉宾：孙文文 博士（澳大利亚莫纳什大学）
时 间： 5月9日（周四）14:00—15:30
报 告 二：Band gap: from the nonempirical dielectric-dependent hybrid functional to the state-of-the-art GW method
主讲嘉宾：刘培涛 博士 （University of Vienna）
时 间： 5月9日（周四）15:30—17:00
活动地点：师昌绪楼403会议室
报告一简介：
本报告将首先主要介绍室温下如何通过非热处理方式使铝合金产生与人工时效热处理相近甚至更优越的强化效果，并解释其中的动态析出相析出机理以及其它的附加优点。其次，介绍“遗传算法”与热力学计算相结合在合金设计中的初步应用，以及所设计出的超高强低合金马氏体时效钢的组织及强化原理，并提出性能改进的方向。
嘉宾一简介：
孙文文，澳大利亚莫纳什大学博士后，长期从事钢铁与铝合金中的相变、力学性能优化、与显微表征方面的研究工作。本科毕业于中南大学和莫纳什大学材料专业，博士毕业于莫纳什大学材料专业，师从Christopher Hutchinson教授。
1. W.W. Sun, Y.M. Zhu, R.K.W. Marceau, L.Y. Wang, Q. Zhang, X. Gao, C.R. Hutchinson*. “Precipitation strengthening of aluminum alloys by room-temperature cyclic plasticity.” Science, 363(2019): 972-975.
2. W.W. Sun, R.K.W. Marceau, M.J. Styles, D. Barbier, C.R. Hutchinson*. “G phase precipitation and strengthening in ultra-high strength ferritic steels: towards lean ‘maraging’ metallurgy.” Acta Materialia, 130 (2017): 28-46.
报告二简介：
Seeking and developing an efficient and robust method for the accurate description of the band gaps of periodic solids continues to be a formidable challenge. Kohn-Sham density functional theory in the LDA or GGA always underestimates the band gaps due to the so-called “self-interaction error (SIE)”. To reduce the SIE and improve the band gap description, hybrid functionals and the state-of-the-art GW method are widely used. In this talk, I will focus on the recently proposed nonempirical dielectric-dependent range-separated hybrid functionals (CAM/DSH) and our recently developed cubic-scaling GW method and its extensions: renormalized GRW0 method and fully self-consistent GW (scGW) method. We identified the connections between different hybrid functionals and assessed the performances of the different methods. We found that single-shot CAM0 and DSH0 outperform conventional hybrid functionals and even the single-shot G0W0 method in the description of band gaps for a large variety of semiconductors and insulators. Our proposed renormalized GRW0 method, which renormalizes the Green’s function by using the one-shot eigenvalues/eigenfunctions of the CAM0/DSH0 Hamiltonian evaluated at the PBE density matrix, while the screened interaction is still evaluated using PBE one-electron energies and orbitals, much improves upon the conventional G0W0 method and are comparable with the eigenvalue self-consistent GW0 (evGW0) method, but with less computational efforts. As expected, without vertex corrections, the full scGW method yields unsatisfactory results. Nevertheless, it paves the way to further improve, for instance, by including the simplest possible vertex W.
嘉宾二简介：
刘培涛，博士，2017年博士毕业于中国科学院金属研究所，师从李殿中和陈星秋研究员。攻读博士学位期间，于2013至2017年在维也纳大学作为联合培养博士生在Georg Kresse教授研究组学习工作。毕业后继续在Georg Kresse教授组从事博士后研究。研究工作主要集中在第一原理计算方法的研发及强关联材料的电子、磁学和光学性质的理论研究。
欢迎所内职工和研究生前来交流！
