The nanoscale material models are molecular dynamics codes and tools used to ascertain properties at the atomistic scale. These simulations generally use interatomic potentials, or force fields, developed using properties obtained from both electronic scale) calculations and experiments, and feed these results into higher scale models, such as dislocation dynamics at the microscale, or continuum models at the macroscale. To date, much of the research at the atomistic scale has focused on informing continuum models for multiscale modeling of metal and polymer material systems. This particular site contains production and research codes that have been developed both at CAVS and outside for performing and analyzing atomistic simulation results. The production codes have user's manuals and a theoretical manual and have been used in practice to solve complex atomistic problems at the nanoscale. The codes that are research codes have not enjoyed the wealth of application and might not have a user's manual or a theoretical manual. We caution the user that there is some risk in using the research version of the codes. Another resource for computational chemistry can be found at computational chemistry.
Finally, to garner more information about the information bridges between length scales go to the Education page.
Tensile Loading of an Aluminum Single Crystal. Movie showing deformation of single crystal aluminum loaded in the <100> direction at a strain rate of 1010 s-1 and a temperature of 300 K.
If you are just beginning with atomistic codes, we recommend that you familiarize yourself with LAMMPS, MATLAB (pre- and post-processing), and some of the visualization codes.
This section shows links to visualization packages used at the atomistic scale. Of these, AtomEye, Ensight, OVITO, and VMD are most frequently used at CAVS. AtomEye, OVITO, and VMD are open source codes.
See the MEAM Parameter Calibration page.
This section includes codes used for preprocessing and postprocessing atomistic results. This section can also include scripts used to generate initial structures for inclusion in molecular dynamics simulations. Additionally, this subsection will include examples of xyz coordinate files that can be used in conjunction with the LAMMPS read_data command to upload.
This project is designed to help introduce high school students to STEM-related 'relevant' research in physics and materials science and engineering.
This section includes links to molecular dynamics codes. LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) is commonly used for many molecular dynamics simulations related to metal and polymer systems at CAVS. LAMMPS' Fortran predecessor WARP can also be used for parallel molecular dynamics simulations. Last, DYNAMO is commonly used for MEAM (modified embedded atom method) interatomic potential generation.
For more information on interatomic potential generation using electronic structure information, use the following links.
This section includes interatomic potential information for atomistic simulations. Embedded atom method potentials can be found at the NIST Interatomic Potential website. A number of modified embedded atom method potentials have been developed here at CAVS for lightweight metals and steel research. Some published and ongoing interatomic potential work at CAVS includes the following:
Movie showing dislocation nucleation from a Sigma 3 asymmetric tilt grain boundary
Coarse Grain SimulationsAn example of tensile deformation in amorphous polyethylene using a united atom method potential.
All Atom SimulationsReactive molecular dynamics simulation of hydrocarbon-based polymers, such as polyethylene and polypropylene, is now possible using the recently parameterized modified embedded-atom method (MEAM) potential for hydrocarbons (C/H system). For more information about the potential, please visit the following link: