Statistical Thermodynamics & Molecular Simulations (STMS) Seminar Series
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. In recent months, the coronavirus pandemic has stopped all 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, however, need to be nominated by their advisors. Seminars will take place on Fridays, from 11 AM-12 PM. During 2021, we expect to hold two seminar per month, at the last two Fridays of each month.This event's talks:
Probing the Adsorption Behavior of Surfactants at Metal-Water Interfaces Using Molecular Simulations
Prof. Sumit Sharma (Ohio University)
Abstract: Adsorption of surfactants is a facile way of adjusting interfacial properties of metals, which has applications in electrochemistry, corrosion inhibition, heterogeneous catalysis and synthesis of anisotropic metal nanoparticles. The traditional viewpoint is that the adsorption of surfactant molecules on metals is driven by a strong affinity of the polar head group of surfactants for metals, and that surfactant molecules adsorb in a planar self-assembled monolayer (SAM). By employing atomistic and coarse-grained molecular simulations as well as statistical mechanics theory, we show that the traditional viewpoint is imprecise on many fronts. We demonstrate that hydrophobic interactions between alkyl tails of surfactants play an active role in the adsorption process. Surfactants adsorb in various morphologies (planar SAM, cylinders and spheres) depending on their molecular geometry. We introduce a new theoretical model that is quantitatively accurate in predicting the various adsorption morphologies of surfactants. Furthermore, we show that the adsorption free energy profiles of surfactants are a function of their aggregation state in the bulk phase – while in infinite dilution, surfactants adsorb strongly on to metal-water interfaces with no free energy barrier, cationic surfactant micelles experience a long-range free energy barrier from the metal surface. Micelles of surfactant molecules adsorb strongly by disintegrating on the metal surface.
Speaker Bio: Dr. Sumit Sharma earned Ph.D. in Chemical Engineering from Columbia University and was a post-doctoral research fellow at Princeton University. Prior to joining Ohio University, he worked as a Yield and Integration Engineer at Intel corporation. His research interests are in molecular simulations and statistical mechanics theory of soft matter, including proteins, polymers and surfactants.
Phase behavior and self-assembly of active colloids
Dr. Stewart Mallory (California Institute of Technology)
ABstract: In recent years, a new type of synthetic microparticle has captured the imagination of researchers across the physical and biological sciences. These so-called active colloids convert chemical or environmental free energy into irreversible directed motion. Impressively, the active force generated by the particles can lead to self-propelling speeds of tens of hundreds of microns per second. Active colloids challenge our theoretical understanding of nonequilibrium phenomena and simultaneously represent a potentially innovative approach to directed transport and material design at the microscale. In this talk, I will discuss one of the most striking features of active colloids, which is their rich and complex nonequilibrium phase behavior. Special emphasis will be given to motility-induced phase separation where purely repulsive active colloids undergo a liquid-gas phase transition. This talk will provide a quantitative understanding of this phenomenon by generalizing concepts in classical statistical mechanics and liquid state theory to active systems.
Speaker Bio: Stewart is currently an Arnold O. Beckman postdoctoral fellow in the Division of Chemistry and Chemical Engineering at Caltech. His research focuses on the development of nonequilibrium theories for the behavior of soft complex materials, with a particular interest in novel techniques to manipulate and self-assemble matter at the colloidal scale. He received his B.S. and B.A. in chemistry and mathematics from the University of Hawai’i and completed his Ph.D. in chemical physics at Columbia University as an NSF Graduate Research Fellow.