Dr. Vassiliy Lubchenko


Dr. Vassiliy Lubchenko

Associate Professor, Department of Chemistry

March 26, 2015, PGH 216, 1PM


Title: When liquids become slow in real life and in the computer: What is inside your rewritable DVD?

Abstract: 

Liquids are amenable to computational approaches because they tend to equilibrate rapidly. For the same reason, liquids quickly assume the shape of the container. In the language of thermodynamics, the liquid state usually has just one free energy minimum. However, when cooled or compressed rapidly, a liquid can become glassy, whereby liquid transport slows down dramatically while the number of the free energy minima begins to scale exponentially with the system size. Searching through these minima can be thought of as a problem whose computational complexity scales exponentially with the system size. I will discuss two instances in which we circumvent some of these computational difficulties by “guessing” the essential physical features of individual solutions and thus greatly reducing the computational complexity of the problem. These guesses are made using the solid state, not liquid state of matter as a mental reference. In one instance, understanding of the physics allows us to solve the long-standing problem of the mysterious midgap electronic states in amorphous chalcogenides. (These are materials used to make optical drives and phase-change computer memory.) In the other instance, we develop a theory of elasticity for solids that do not possess a unique vibrational ground state, a setup formally analogous to the multiverse. Requisite notions of thermodynamics will be reviewed during the lecture.  

Bio:  

Vas Lubchenko is Associate Professor of Chemistry at the University of Houston. His research interests include amorphous materials, the glass transition, protein aggregation, and solid state inorganic chemistry. He received his Ph.D. in Physical Chemistry from the University of Illinois at Urbana-Champaign. He has been awarded by the Beckman Young Investigator Award, Sloan Research Fellowship, and the NSF CAREER Award.