WIELD - (W)eak approximation of (I)nterface (E)nergy for bicrysta(L) boun(D)aries

This is a small research program to compute the energy of a bicrystal interface (grain boundary). This implements the lattice-matching method for GB energy and CSL used in (among others):

• https://doi.org/10.1016/j.jmps.2016.01.008
• https://doi.org/10.1016/j.jmps.2015.11.007
• https://doi.org/10.1107/S205327331700122X
• https://doi.org/10.1016/j.mtla.2019.100221
• https://doi.org/10.1016/j.scriptamat.2020.04.042
• https://doi.org/10.1016/j.actamat.2021.117149
• https://doi.org/10.1016/j.commatsci.2023.112057

There are two main interfaces for wield, the python interface and the input file interface. The python interface is recommended as it will be more continuously supported.

Python Interface

The python interface supports interaction with wield structures and methods by import wield.

Dependencies

Installation of dependencies using aptitude or yum can be done by running the following scripts.

Debian-based distributions (Ubuntu) using apt

RPM-based distributions (RHEL,Fedora) using yum

Installation

If you have not already, clone the repository with:

git clone https://github.com/solidsgroup/wield.git

Now install using pip:

pip3 install --user -e wield/py

(The --user and -e options are not required but are recommended)

Now you can import wield and use wield functions in python, e.g.

import wield
wield.createMatrixFromXAngle(0.0)

Run tests

Current tests are stored in the tests directory. To run, execute with python; for instance,

cd tests/csl_fcc_110
python3 input.py

Input File Interface

The input file interface is a legacy method for interacting with wield. It is not currently maintained, so use at your own risk.

Dependencies

The following external packages are required for Wield.

1. MuParser: available in the Ubuntu repository as libmuparser-dev

2. TCLAP: available in the Ubuntu repository as libtclap-dev

3. Python developer tools: available in the Ubuntu repository as python3-dev

Compilation

Wield compiles using the Makefile. In the root directory type

make

Usage

Running the program:

./main [input file] [-D.= ... ] [-p --dynamic-plot] [-n --num-threads ] [-h --help]

Runtime variables

All runtime variables can be specified in one of two ways:

• In the input file

$VarName varvalue $StructName { $VarName varvalue }

• In the command line

./main -DVarName=varvalue -DStructName.VarName=varvalue

Command line options

Some routines support additional command line options:

• -p --dynamic-plot: for some supported functions, a VTK window will be displayed that shows the results of the computation real-time.
• -n --num-threads : for some supported functions, use pthread parallelism

Methods

This program is a collection of other methods that can be run seperately or simultaneously. Use the following links to find documentation and example input files for each method

• \ref Wield::Main::CSL Compute the thermalized coincident site lattice \f$\Sigma\f$ value of a bicrystal
• \ref Wield::Main::Energy1D Compute the thermalized grain boundary energy for an interface
• \ref Wield::Main::MainInterface1D Compute the interface energy as a function of interface orientation, parameterized by one angle
• \ref MainFacet2D Use the relaxation algorithm to compute the facet pattern and relaxed energy, given an energy surface

Documentation

You can use doxygen to generate documentation for Wield by typing

doxygen

in the main directory. (Note: you must have Doxygen installed.) The HTML documentation main page is located at dox/html/index.html