A5068520992- Parallel Computing and Optimization Techniques
- Advanced Data Storage Technologies
- Material Dynamics and Properties
- Distributed and Parallel Computing Systems
- Gas Dynamics and Kinetic Theory
- Theoretical and Computational Physics
- Microstructure and mechanical properties
- Advanced Memory and Neural Computing
- Granular flow and fluidized beds
- Electron and X-Ray Spectroscopy Techniques
- Neural Networks and Applications
- Machine Learning in Materials Science
- Fluid Dynamics Simulations and Interactions
- Phase Equilibria and Thermodynamics
- Rheology and Fluid Dynamics Studies
- Mathematics, Computing, and Information Processing
- Advanced Chemical Physics Studies
- Advanced NMR Techniques and Applications
- Fluid Dynamics and Turbulent Flows
- High-Velocity Impact and Material Behavior
- Advanced Materials Characterization Techniques
- Interconnection Networks and Systems
- Spectroscopy and Quantum Chemical Studies
- Advanced Physical and Chemical Molecular Interactions
- Electromagnetic Simulation and Numerical Methods
Temple University
2024
Sandia National Laboratories California
2009-2023
Sandia National Laboratories
2013-2022
National Technical Information Service
2003-2010
Office of Scientific and Technical Information
2003-2010
The University of Texas at Austin
2008
Wabash College
2006
University of Chicago
2006
University of Illinois Urbana-Champaign
2006
Illinois Institute of Technology
2006
Since the classical molecular dynamics simulator LAMMPS was released as an open source code in 2004, it has become a widely-used tool for particle-based modeling of materials at length scales ranging from atomic to mesoscale continuum. Reasons its popularity are that provides wide variety particle interaction models different materials, runs on any platform single CPU core largest supercomputers with accelerators, and gives users control over simulation details, either via input script or by...
We model indentation of a metal surface by combining an atomistic with hard-sphere indenter. This work provides imaging dislocation nucleation during displacement controlled on passivated surface. Dislocations and defects are located imaged local deviations from centrosymmetry. For Au(111) surface, partial loops occurs below the inside indenter contact area. compare contrast these observations empirical criteria for corresponding continuum elasticity solutions.
We present the results of a large scale molecular dynamics computer simulation study in which we investigate whether supercooled Lennard-Jones liquid exhibits dynamical heterogeneities. evaluate non-Gaussian parameter for self part van Hove correlation function and use it to identify ``mobile'' particles. find that these particles form clusters whose size grows with decreasing temperature. also relaxation time mobile is significantly shorter than bulk, this difference increases
We have performed a systematic, large-scale simulation study of granular media in two and three dimensions, investigating the rheology cohesionless particles inclined plane geometries, i.e., chute flows. find that over wide range parameter space interaction coefficients inclination angles, steady-state flow regime exists which energy input from gravity balances dissipated friction inelastic collisions. In this regime, bulk packing fraction (away top free surface bottom plate boundary)...
A large-scale molecular dynamics simulation is performed on a glass-forming Lennard-Jones mixture to determine the nature of dynamical heterogeneities which arise in this model fragile liquid. We observe that most mobile particles exhibit cooperative motion form string-like paths (``strings'') whose mean length and radius gyration increase as liquid cooled. The distribution strings found be similar expected for equilibrium polymerization linear polymer chains.
Three distinct forms are derived for the force virial contribution to pressure and stress tensor of a collection atoms interacting under periodic boundary conditions. All three written in terms forces acting on atoms, so valid arbitrary many-body interatomic potentials. mathematically equivalent. In special case with pair potentials, they reduce previously published forms. (i) The atom-cell form is similar standard expression finite nonperiodic system, but an explicit correction interactions...
Several methods for preparing well equilibrated melts of long chains polymers are studied. We show that the standard method in which one starts with an ensemble correct end-to-end distance arranged randomly simulation cell and introduces excluded volume rapidly, leads to deformation on short length scales. This is strongest relaxes only after have moved their own size. Two shown overcome this local chains. One first pre-pack Gaussian chains, reduces density fluctuations system, followed by a...
Nonvolatile redox transistors (NVRTs) based upon Li-ion battery materials are demonstrated as memory elements for neuromorphic computer architectures with multi-level analog states, "write" linearity, low-voltage switching, and low power dissipation. Simulations of backpropagation using the device properties reach ideal classification accuracy. Physics-based simulations predict energy costs per operation <10 aJ when scaled to 200 nm × nm.
Using extensive molecular dynamics simulations of an equilibrium, glass-forming Lennard-Jones mixture, we characterize in detail the local atomic motions. We show that spatial correlations exist among particles undergoing extremely large ("mobile") or small ("immobile") displacements over a suitably chosen time interval. The immobile form cores relatively compact clusters, while mobile move cooperatively and quasi-one-dimensional, stringlike clusters. strength length scale between are found...
The gold-standard definition of the Direct Simulation Monte Carlo (DSMC) method is given in 1994 book by Bird [Molecular Gas Dynamics and Flows (Clarendon Press, Oxford, UK, 1994)], which refined his pioneering earlier papers he first formulated method. In intervening 25 years, DSMC has become choice for modeling rarefied gas dynamics a variety scenarios. chief barrier to applying more dense or even continuum flows its computational expense compared fluid methods. dramatic (nearly...
Resistive memories enable dramatic energy reductions for neural algorithms. We propose a general purpose architecture that can accelerate many different algorithms and determine the device properties will be needed to run backpropagation on architecture. To maintain high accuracy, read noise standard deviation should less than 5% of weight range. The write 0.4% range up 300% characteristic update (for datasets tested). Asymmetric nonlinearities in change conductance vs pulse cause decay...
The time evolution of species concentrations in biochemical reaction networks is often modeled using the stochastic simulation algorithm (SSA) [Gillespie, J. Phys. Chem. 81, 2340 (1977)]. computational cost original SSA scaled linearly with number reactions network. Gibson and Bruck developed a logarithmic scaling version which uses priority queue or binary tree for more efficient selection [Gibson Bruck, A 104, 1876 (2000)]. More generally, this problem one dynamic discrete random variate...
We present a review and critique of several methods for the simulation dynamics colloidal suspensions at mesoscale. focus particularly on techniques hydrodynamic interactions, including implicit solvents (Fast Lubrication Dynamics, an approximation to Stokesian Dynamics) explicit/particle-based (Multi-Particle Collision Dynamics Dissipative Particle Dynamics). Several variants each method are compared quantitatively canonical system monodisperse hard spheres, with particular diffusion...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Michael A. Gallis, John R. Torczynski, Steven J. Plimpton, Daniel Rader, Timothy Koehler; Direct simulation Monte Carlo: The quest for speed. AIP Conf. Proc. 9 December 2014; 1628 (1): 27–36. https://doi.org/10.1063/1.4902571 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley...