QC Code: Quasicontinuum (QC) is a multiscale method in which adaptive fully-resolved atomistic regions modeled via molecular statics or molecular dynamics are embedded within a coarse-grained continuum modeled via nonlinear finite elements employing the Cauchy-Born rule. This makes it possible to simulate meso and macro scale system with atomistic resolution where necessary at a fraction of the cost of fully-atomistic simulations.
- A 2D version of the of the QC code limited to simple lattice crystal (i.e. crystals with one atom per unit cell) is freely available for download. The code has several features including support for polycrystal materials, adaptive meshing, and efficient conjugate gradient and Newton-Raphson solvers. A tutorial and reference manual are provided with the code. The QC package is available for download at http://qcmethod.org/qc/download.
- A 3D high-performance computing (HPC) implementation of the code (qc3d) supports arbitrary multilattice polycrystalline systems at both zero and finite temperature. Temporal acceleration using hyperdynamics is also included. This code is not available for distribution at this time, but collaborations on mutual problems of interest is possible. If interested, contact Prof. Tadmor at the email address above.
KIM Application Programming Interface (API): The KIM API is an Application Programming Interface for atomistic simulations. The API provides a standard for exchanging information between atomistic simulation codes (molecular dynamics, molecular statics, lattice dynamics, Monte Carlo, etc.) and interatomic models (potentials or force fields). It also includes a set of library routines for using the API with bindings for Fortran (77, 90 and 2003), C and C++. By conforming to this API, an atomistic simulation code will seamlessly work with any KIM-compliant interatomic model written in any supported language. The interface is computationally efficient and often requires relatively minor changes to existing codes.
The code is available at https://openkim.org/kim-api/.
MDStressLab is a KIM-compliant program for postprocessing molecular dynamics or
molecular statics results to obtain stress fields using different definitions of
the atomistic stress tensor. MDStressLab has the following capabilities/features:
(1) Calculate fields of the Cauchy and first Piola-Kirchhoff versions of the Hardy, Tsai and virial stress tensor in two and three dimensions on a user-specified grid;
(2) Decompose the atomistic stress tensor into a unique irrotational part and a non-unique solenoidal part.
(3) Stress filtering to obtain smooth stress fields in the vicinity of defects and other stress concentrations in crystalline systems.
A user manual is provided with the code. MDStressLab is available for download at
Thermal Parameter Identification (TPI): TPI is a method for computing the thermal parameters associated with the non-Fourier Cattaneo-Vernotte and Jefreys-type models for heat transfer (thermal conductivity and one or two relaxation times) from a series of predesigned nonequilibrium molecular dynamics (MD) simulations. The code and files necessary to carry out a TPI calculation are freely available. The TPI archive, which contains documentation for using the method, input files and extensions needed to use the LAMMPS MD program to perform the required MD simulations, and a MATLAB program for processing the LAMMPS output to obtain the thermal parameters, is available here (gzipped tar file). (To unpack the pacakge, use the following Linux/Unix command: "tar zxvf tpiv2.tgz". This will create the directory TPI_v2. To start, read the README file in this directory.)