Statistical Thermodynamics & Molecular Simulations (STMS) Seminar Series

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These seminar series are aimed at providing a virtual platform for sharing scientific research in the area of statistical mechanics, molecular simulations, and computational materials science. Since early 2020, the coronavirus pandemic has disrupted many large in-person scientific gatherings, including conferences and department seminars, and it is not clear that the situation will improve any time soon. STMS is aimed at filling this gap, and provide a venue for dissemination of research findings and exchange of ideas in the age of COVID.  This model is being currently used by several other scientific communities, and can potentially continue even beyond the pandemic if successful. 

Each seminar will be a 60-minute event and will comprise of a long-form (30-minute) talk by a principal investigator or a senior research scientists from academia or industry and a short-form (15-minute) presentation by a graduate student or a postdoc. The remainder of the event will be dedicated to Q&A (10 minutes for the PI, 5 minutes for the student/postdoc). Long-form speakers will be chosen by the STMS Organizing Committee, while we encourage suggestions from the community at large. Student and postdoctoral speakers can either be nominated by their advisors or can self-nominate themselves by sending a CV to the organizers.  During 2022 we expect to hold two seminar per month, and the events will take place in the last two Fridays of each month, from 10:45 AM-12:00 PM Eastern Standard Time (EST):

This event's talks:

A theory of entropic bonding

Prof. Sharon Glotzer (University of Michigan)

Abstract: Many atomic and molecular crystal structures– made possible by chemical bonds – can now be realized at larger length and time scales for nanoparticles and colloids via physical bonds, including entropic bonds. The structural similarities between colloidal crystals and atomic crystals suggest that they should be describable within analogous, though different, conceptual frameworks. In particular, like the chemical bonds that hold atoms together in crystals, the statistical, emergent, entropic forces that hold hard colloidal particles together in colloidal crystals should be describable using the language of bonding. In this talk, we present a microscopic, mean-field theory of entropic bonding that permits prediction of colloidal crystals in a way that is mathematically analogous to the first principles prediction of atomic crystals by solving Schrödinger’s equation or variants thereof. We show how solutions to the theory are facilitated by the use of mathematically constructed shape orbitals analogous to atomic orbitals, using the same algorithms used in modern electronic structure codes for atomic crystal prediction. 

Speaker Bio: Sharon C. Glotzer is the John W. Cahn Distinguished University Professor of Engineering and the Stuart W. Churchill Collegiate Professor of Chemical Engineering and Professor of Materials Science and Engineering at the University of Michigan, Ann Arbor, and also holds faculty appointments in Physics, Applied Physics, and Macromolecular Science and Engineering. Since July 2017 she is the Anthony C. Lembke Department Chair of Chemical Engineering at the University of Michigan. Her research on computational assembly science and engineering aims toward predictive materials design of colloidal and soft matter. Using computation, geometrical concepts, and statistical mechanics, her research group seeks to understand complex behavior emerging from simple rules and forces, and use that knowledge to design new materials. Glotzer’s group also develops and disseminates powerful open-source software including the particle simulation toolkit, HOOMD-blue, which allows for fast molecular simulation of materials on graphics processors, the signac framework for data and workflow management, and several analysis and visualization tools.   (https://github.com/glotzerlab/)

Glotzer received her Bachelor of Science degree in Physics from UCLA and her PhD in Physics from Boston University.  She is a member of the National Academy of Sciences, the National Academy of Engineering, and the American Academy of Arts and Sciences. She is a Fellow of the Materials Research Society, the American Association for the Advancement of Science, the American Institute of Chemical Engineers, the American Physical Society, and the Royal Society of Chemistry. Glotzer is the recipient of numerous awards and honors, including the 2019 Aneesur Rahman Prize for Computational Physics from the American Physical Society, the 2018 Nanoscale Science and Engineering Forum and the 2016 Alpha Chi Sigma Awards both from the American Institute of Chemical Engineers, and the 2019 Fred Kavli Distinguished Lectureship in Materials Science, 2017 Materials Communications Lecture Award and 2014 MRS Medal from the Materials Research Society. Glotzer is a leading advocate for simulation-based materials research, including nanotechnology and high performance computing, serving on boards and advisory committees of the National Science Foundation, the U.S. Department of Energy, and the National Academies. She is currently a member of the National Academy of Sciences Division on Engineering and Physical Sciences Committee.  

Engulfment of antifreeze proteins by ice

Dr. Aniket Thosar (University of Pennsylvania)

Abstract: Antifreeze proteins (AFPs) are a remarkable class of proteins, which enable diverse organisms, from fishes and insects to plants and bacteria, to survive in frigid polar environments. Despite being present at millimolar concentrations, AFPs help the host organisms survive at sub-freezing temperatures by suppressing ice formation. To function, AFPs must perform one of the most challenging recognition tasks in all of biology: - binding an ice nucleus in a vast excess of water even though there are no chemical and few structural differences between ice and water. Once AFPs bind the ice nucleus, ice growth can occur only if ice is successful in engulfing the bound AFPs. At a sufficiently low temperatures (below the melting point), the driving force for ice growth wins over the unfavorable process of AFP engulfment and AFPs are no longer able to resist the ice growth. The range of temperatures over which AFPs are able to suppress ice growth, known as the thermal hysteresis activity of the AFP, varies from one AFP to another. To uncover how the molecular characteristics of an AFP influence its activity, we employ molecular dynamics simulations and enhanced sampling techniques. We characterize the free energetics of engulfment of AFP by ice to understand how the thermal hysteresis activity of an AFP depends not only on the separation between AFPs, but also on AFP size, shape, and chemistry.

 Speaker Bio: Aniket Thosar obtained his PhD in Engineering Sciences from National Chemical Laboratory, India. His PhD work, supervised by Dr. Ashish Lele, focused on proton exchange membrane (PEM) fuel cell technology, a device that converts chemical energy of hydrogen into electricity. He derived physics-based design equation of PEM fuel cells that relates its parametric space with electrical power output. Subsequent to his PhD, he began working with Prof. Amish Patel at University of Pennsylvania on deciphering the structure-ice growth inhibition activity relationship of antifreeze proteins, which has important implications in the diverse fields ranging from organ preservation to food preservation.   

 

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