MateriAlZ Seminar: Zi-Kui Liu
Friday, October 7, 2022, 11:00 a.m. (Arizona Time)
Zi-Kui Liu
Dorothy Pate Enright Professor of Materials Science and Engineering
Pennsylvania State University
"Zentropy Theory: A Predictive Approach Based on Quantum Mechanics and Statistical Mechanics"
Harshbarger 332
Zoom link | Passcode: 605042
MateriAlZ Seminar website | YouTube | Twitter
Abstract
Experimental observations represent the responses of the system to external stimuli. Their predictions remain a key challenge in science. Based on the second law of thermodynamics, entropy drives all internal processes in systems. While the total entropy of a system can be accurately obtained by integration of experimentally measured heat capacity, its theoretical prediction remains elusive due to the difficulty in computationally sampling all configurations in the system. Entropy of a system is counted theoretically by statistical mechanics, in which the partition function of a system equals to the sum of the partition function of independent configurations of the system, and the probability of a configuration equals to the ratio of its partition function to the partition function of the system. The entropy of the system is thus obtained by the Gibbs distribution of the configurations, which implies that each configuration is a pure quantum state with zero entropy, while configurations at typical experimental scales are not pure quantum states. In our newly termed zentropy theory, the contributions from individual configurations to the total entropy of the system are considered, resulting in the replacement of the total energy of each configuration in its partition function by its free energy and a nested formula to account for disorder and fluctuations from the electronic scale to the experimental scale. In this presentation, the zentropy theory is introduced, and its capability is demonstrated through parameter-free prediction of emergent behaviors in magnetic and ferroelectric materials including singularity at critical points.
Bio
Zi-Kui Liu is the Dorothy Pate Enright Professor of Materials Science and Engineering at Pennsylvania State University. He obtained his BS from Central South University (China), MS from the University of Science and Technology Beijing (China) and Ph.D. from the Royal Institute of Technology (KTH, Sweden). He was a research associate at the University of Wisconsin-Madison and a senior research scientist at Questek Innovation, LLC. He has been at Pennsylvania State University since 1999 and his current research activities are centered on first-principles calculations, machine learning, prediction and modeling of thermodynamic, kinetic and mechanical properties, and their integration for understanding defects, phase stability, and phase transformations, and designing materials processing and properties. Dr. Liu has been the Editor-in-Chief of CALPHAD journal since 2001 and the President of CALPHAD, Inc. since 2013. He is Fellow of ASM International and TMS and served as the President of ASM International and a member of ASM Board of Trustees and the TMS Board of Directors. Dr. Liu coined the term “Materials Genome®” in 2002.