物理科学与技术学院物理讲坛（2019年第10-12讲）

报告题目：First Principles Design of Materials for Optoelectronic Device Applications

报告人：魏苏淮，讲座教授

单 位：北京计算科学研究中心

报告时间：2019年7月2日 下午 13:30-14:30

报告地点：赛思学术会堂
报告摘要：Materials design using first-principles techniques is one of the ultimate goals in computational materials science. Recent advances in first-principles electronic structure theory and computing power has enabled us to perform knowledge-based computational design of materials with unique optoelectronic properties that are tuned to specific applications. This approach has now become a vital tool in accelerating scientific discovery of optoelectronic materials. In this talk, selective topics from our recent studies will be discussed to illustrate how computational methods can be used to understand and design functional optoelectronic materials, including solar-electric materials; solar-chemical materials; and transparent conducting materials.

报告题目：Applications of ab initio method to high-entropy alloys

报告人：田付阳，副教授

单 位：北京科技大学

报告时间：2019年7月2日 下午15:00-16:00

报告地点：赛思学术会堂
报告摘要：Due to the unique microstructures and special properties, since 2004, the high-entropy alloys (HEAs) composed of multi components make one re-understand the theory on metals, for example, the excellent ductility at low temperature and the unusual stacking fault energy, etc. As a typical solid solutions, HEAs have the large degree of uncertainty and result in the difficulty in the regular ab initio calculation. Recently, we used the effective medium and supercell method in combination with ab initio method to calculate the electronic energy dispersion, the equation of state, the stacking fault energy, elastic constants, local lattice distortion, short-range order etc. For 3d-HEAs, the magnetism plays an important role in the stability of phase. The average field based coherent potential approximation can be used to calculate well the elastic constants and stacking fault energy. We can exactly describe the local lattice distortion and short-range order with the supercell method based on the similar atomic environment model.

报告题目：Tilings Self-Assembled from Rod-Coil Block Copolymers with Hydrogen Bonds

报告人：唐萍，教授

单 位：复旦大学

报告时间：2019年7月2日 下午 16:30-17:30

报告地点：赛思学术会堂
报告摘要：We demonstrate that X-shaped rod-coil molecules with hydrogen-bonding groups can self-assemble into Archimedean tiling patterns, by using self-consistent field theory (SCFT) calculations. The rod blocks form the polygon edges with coil blocks filling in the inner spaces of polygons as shown in Figure 1. The existence of hydrogen bonds further decreases the domain size. A new mechanism is proposed to guide the formation of Archimedean tiling patterns. The formation of tiling patterns is controlled by the relationship between the length to diameter ratio and volume fraction of rigid cores. Furthermore, the blend of two kinds of X-shaped molecules, namely one with two distinct lateral the other with two same lateral chains at the middle of rod chains, is proposed to investigate the formation of tiling patterns with n-polygons with n larger than 6.