Speaker: Dr. Qiang Zhu, Department of Geosciences, Stony Brook University, Stony Brook.
Abstract: Crystal structure prediction used to be impossible challenge in physical science for a long time. The situation began to dramatically change in the last decade. The recently developed evolutionary algorithm (EA) USPEX proved to be a tool that enables accurate and reliable prediction of structures for a given chemical composition at given pressure temperature conditions. USPEX has been successfully used to predict the stable structure a wide range of materials, and explore the novel physics and chemistry under extreme conditions.How evolutionary crystal structure prediction works - and why? In this talk, I will summarize the principles, developments, and applications of the USPEX code in the past years. In further, I will present some extended functions:
1) Variable compositional prediction. A scheme is proposed to simultaneously optimizing both chemical compositional space and energy space. With the smart operators in EA approach to enable stoichiometric variation, it allows the automatic search for all the stable compounds in the given system (Na-Cl, Mg-O, MgO-SiO2, etc) .
2) Predicting structures from structural motifs. We designed a constrained evolutionary algorithm. The key feature of this new approach is that each motif is treated as a (partially) rigid building block. This method significantly reduces the search space, and it can applied to a wide range of systems including inorganic complex, molecular crystals, polymers and even molecular compounds, and even pharmaceutical co-crystals
3) Predicting low dimensional system. Different from bulk crystals, surface brings another in-dependent thermodynamical parameter, chemical potential. Since the stability of surface configuration depends on the chemical potential, the established convex hull for multi-component system is quite different.
4) Optimizing physical properties. If the physical properties are set as the global optimizing target, while structure relaxations are energy/enthalpy minimization, such hybrid optimization technique could effectively explore the landscape of properties (hardness, density,etc.) for the given systems.
About the Speaker: During under/post-graduate, Dr. Zhu Qiang was focusing on computational material & mineral sciences, covering multi-scale modeling of materials (including finite element, classical molecular dynamics and ab initio MD). At present, he is a postdoctoral research fellow in Department of Geosciences in State University of New York at Stony Brook. He is currently working on methodology development of crystal structure prediction as implenmented in the USPEX code.
Date&Time: July 29, 2013 (Monday), 16:00 – 17:00
Location: 606 Conference Room
