Juan P. Hernandez, Juan J. de Pablo, and M. Graham, Physical Review Letters , 98, 140602, 2007

1. General Method for Modeling of Nanoparticle Dynamics far from EquilibriumPaul F. Nealy, University of Wisconsin-Madison, NSEC, DMR 0425880Juan P. Hernandez, Juan J. de Pablo, and M. Graham One of nanotechnology’s central aims is to conceive – an implement – complex processes at the nanoscale. Distinct components of a nanoscale device must be positioned and assembled with nanometer precision, reproducibly, and, if possible, in a high throughput manner. To that end, researchers have explored the use of external fields, e.g. the use of flow or voltage to move nanoscale objects around. Much of this work has been largely empirical; predictions of the way in which flow fields and electrical fields influence the motion of nanoscale objects have been hampered by a lack of fast and efficient numerical algorithms capable of computing the effects of hydrodynamic interactions. Recently, UW NSEC researchers have developed a fast and robust algorithm for computation of long-range interactions, including electrostatic and hydrodynamic, in arbitrary geometries. In a recent publication in Physical Review Letters, 98, 140602, 2007, NSEC postdoctoral student Juan Pablo Hernandez introduced the so-called “General Geometry Ewald-like Method” (GGEM), which, for the first time, has permitted study of concentrated solutions of DNA far from equilibrium and under extreme confinement, study of the driven assembly of b-peptide nanorods, and simulations of charged dipolar particles. The GGEM algorithm will facilitate considerably the rational design of complex nanofluidic devices by permitting fast, detailed predictive simulations of dilute and concentrated suspensions of nanoscale objects, both at equilibrium and far from equilibrium. Schematic representation of the traces left behind as a collection of DNA molecules flow through a small constriction, under the influence of pressure,  Brownian forces,  and hydrodynamic interactions. Juan P. Hernandez, Juan J. de Pablo, and M. Graham, Physical Review Letters, 98, 140602, 2007