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:
Mapping free energy landscapes for soft materials
Prof. Jonathan Whitmer (University of Notre Dame)
Abstract: Soft materials, encompassing (but not limited to) polymers, colloids, and liquid crystals, are fascinating systems where molecular interactions often conspire to create new phases and emergent properties. Free energies provide essential information about the properties and structure of these materials. Still, their calculation can be demanding, as the systems are complex, and meaningful analytical approximations may not be present. Advanced simulation algorithms are essential computational tools that enable us to unravel critical assembly pathways and determine the free energetic driving forces controlling materials' behavior under various conditions. In this talk, I will present an overview of recent efforts within my group to compute free energies using advanced sampling algorithms and discuss their application to studies of self-assembly, effective interactions, and free energy barriers in materials systems.
Speaker Bio: Jonathan K. Whitmer is an Associate Professor of Chemical and Biomolecular Engineering at the University of Notre Dame. He holds BS degrees in Math and Physics from Kansas State University and MS and PhD degrees in Physics from the University of Illinois (working with Erik Luijten). He joined Notre Dame in 2014 after a postdoc with Juan de Pablo at the University of Wisconsin and later Argonne National Laboratory. He received an NSF CAREER award in 2018, and his group develops the open source software SSAGES (Software Suite for Advanced General Ensemble Simulations) in collaboration with MICCoM, a DOE Computational Materials Science center located at Argonne National Laboratory.
Colloidal crystal reconfiguration via dislocation machines
Dr. Bryan vanSanders (University of Chicago)
Abstract: Colloidal nanoparticles that exert local forces suggest a future class of swarm metamaterials. These swarms must coordinate their actions to accomplish useful tasks, such as changing the shape of the swarm or engulfing an object. Changing the swarm shape requires mass flow – for large swarms restricting the flow to the surface presents a bottleneck. I show, through computer simulation, how crystalline defects can be harnessed to organize volumetric mass transport in dense aggregations of colloidal particles. Plastic deformation of crystalline materials proceeds by the creation and migration of dislocations under the influence of external forces. If dislocations are instead produced and migrated due to forces exerted by particles locally, then large-scale material shape change can occur by microscopic control. I demonstrate how clusters of particles with variable diameters embedded in a colloidal monolayer can produce dislocations on demand by swelling. By engineering the shape of the embedded cluster, a repeatable cycle of dislocation creation and motion can be achieved that unlocks the ability to perform large-scale reconfiguration with actuation of only a single degree of freedom. The embedded cluster which produces dislocations acts as a microscopic ‘dislocation machine’, directionally emitting dislocations and controlling the configuration of the larger ensemble. These results are also applicable to larger-scale swarms of robotic particles that organize into dense ordered two-dimensional arrangements.
Speaker Bio: Bryan VanSaders is currently a Kadanoff-Rice postdoctoral fellow at the University of Chicago, working with Professors Heinrich Jaeger and Vincenzo Vitelli. He earned his PhD in Materials Science and Engineering from the University of Michigan, working with Professor Sharon Glotzer. He uses computer simulation to study active soft matter systems, which present new possibilities for manipulating matter at the microscopic scale. He is particularly interested in the intersection of active matter and topological defects in dense crystalline colloidal assemblies. He also studies nonequilibrium methods of driving soft material assembly through acoustic and electrical fields.