Flexibility, Structural Transitions and Quantum Geometry of Electrons in Crystals (10/01/24)

Department of Materials Engineering, Indian Institute of Science, Bangalore
Indian Institute of Metals -Bangalore Chapter

Third Lecture of the
PROF. S. RANGANATHAN Distinguished Lecture Series

Speaker and Affliation:

Prof. Umesh V Waghmare
Dean-Faculty and Professor
Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore


10th January, 2024 (Tuesday), 11.00 AM (India Standard Time)


KPA Auditorium, Dept. of Materials Engineering, IISc, Bangalore


While the structural stability of a material and its mechanical behaviour are central to any of its applications, its instabilities are responsible for structural transitions with interesting signatures in its functional properties of technological relevance. We first illustrate this with exotic ferroelectricity in HfO2, which has the potential to be useful in the development of ultimately high-density memory chips. We then present an analysis of entropic stabilization and descriptors of structural transition in a high entropy alloy NbHfZrTi, demonstrating how the internal lattice distortions peak at the transition. The flexibility of geometrically interesting framework crystals, such as metal-organic frameworks, is important to their applications. While closely linked to rigidity, a precise measure if flexibility has been lacking. We present a quantitative measure of mechanical flexibility and uncover its mechanisms from the analysis of different types of crystalline materials. Finally, we introduce the quantum geometry of the electronic structure in a crystal, its intimate link with certain metallic states, and illustrate how it influences anomalies in measurable properties.


Prof. Umesh Vasudeo Waghmare, currently serving as Dean-Faculty and Professor in the Theoretical Sciences Unit at Jawaharlal Nehru Centre for Advanced Scientific Research, holds a B Tech from IIT Bombay (1990) and a PhD from Yale University (1996). He is also a JC Bose National Fellow, President of the Indian Academy of Sciences, and a distinguished adjunct professor at Temple University. Waghmare’s research focuses on ab initio theory, multifunctional materials, nanostructures, topological insulators, and materials for energy and the environment. He has received numerous awards, including the Infosys Prize in Engineering and Computer Science (2015). He is an Associate Editor of NanoScale and NanoScale Advances and serves on the Editorial Advisory Boards of the Journal of American Chemical Society and Materials Today. Recognized as a distinguished alumnus by IIT Bombay in 2017, Waghmare is an elected Fellow of the National Academy of Sciences, Allahabad, the Indian National Science Academy, and the Indian National Academy of Engineering.