COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER AND THE DEPARTMENT OF COMPUTATIONAL AND DATA SCIENCES – Using Coarse-Grained Models to Access Expanded Length and Time Scales for Nanoscience Applications – K. Michael Salerno, Jr.
COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
AND THE DEPARTMENT OF COMPUTATIONAL AND DATA SCIENCES
(CSI 898-Sec 001)
Using Coarse-Grained Models to Access Expanded Length and Time Scales for Nanoscience Applications
K. Michael Salerno, Jr.
Center for Computational Materials Science
Naval Research Laboratory
November 14, 4:30 pm
Exploratory Hall, Room 3301
Polymers and other soft materials have an important role as a coating for nanoscale building blocks like metallic nanoparticles (NPs) and nanorods. This coating mediates interactions between these building blocks and their environment. Atomistic molecular dynamics (MD) simulations are ideal for examining the role of chemistry and atomic interactions at the sub-nanometer scale, for example in the interactions between a NP and a solvent, or between pairs of NPs. Unfortunately, atomistic MD simulations are limited to lengths of order 50 nm and times of order 50 ns. The time scale limitation precludes modeling nanoscale self-assembly, and limits dynamic simulations to extremely high rates of deformation or thermalforcing. These simulations are also limited to sizes that represent a small number of NPs, making it impossible to model large assembled structures.
Faced with these limitations, we have developed coarse-grained (CG) models of polyethylene, a simple polymer used to coat NPs and nanorods. These models have enabled simulations of bulk polymer melts that overcome the limits of atomistic MD by providing a computational speedup of greater than 104 while retaining fundamental details at the sub-nanometer scale. These details produce the viscoelastic properties and semi-crystalline behavior that are intrinsic to polyethylene and that are missed by generic CG models. When applied to a NP coating the CG models capture the coating morphology, indicating the value of using these CG models in nanoscale applications.
Refreshments will be served at 4:15 PM.
Find the schedule at http://www.cmasc.gmu.edu/seminars.htm