ABOUT THIS REPO

This respository holds C++ code that numerically computes Brownian coating and substrate thermal noise for amorphic and crystalline materials. Results from this code are presented in https://doi.org/10.1088/1361-6382/aa9ccc.

If you make use of this code, please cite technical report https://doi.org/10.1088/1361-6382/aa9ccc.

The primary requirement for compiling and running this code is the deal.II framework (http://www.dealii.org). It also requires petsc, and you'll need MPI to run on multiple processors.

BUILDING AND USING

Instructions for building this code, and example use cases, will be added here.

Meanwhile, once you have installed deal.ii (dealii.org) and petsc (petsc.org) with the hypre package and p4est (and other dealii dependences), you can build and run the code "QuasistaticBrownianThermalNoise.cpp" similarly to how you build and run the deal-ii step-8 tutorial (https://www.dealii.org/8.4.0/doxygen/deal.II/step_8.html).

I recommend first ensuring that you can build and run the deal.II tutorials step-3 (Laplace equation), step-8 (2D elastic equations), and step-17 (petsc + MPI Laplace equation).

You'll need to install the following dependencies:

• yaml-cpp

To build yaml-cpp, you can do this:

git clone https://github.com/jbeder/yaml-cpp
cd yaml-cpp
git checkout yaml-cpp-0.6.2
mkdir -p ~/Codes/yaml/0.6.2
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=${HOME}/Codes/yaml/0.6.2 ..
make
ctest
make install

To build and run the thermal noise code, e.g., do this:

cd /path/to/QuasistaticBrownianThermalNoise.cpp
mkdir build
cd build

cmake .. -DYAMLCPP_ROOT=/Users/geoffrey/Codes/dealii/yaml/yaml-cpp/0.6.2/ -DCATCH_ROOT=/Users/geoffrey/Codes/dealii/NumericalCoatingThermalNoise/NumericalCoatingThermalNoise/external/ -DPROCS_FOR_TESTS=4 -DCMAKE_FIND_LIBRARY_PREFIXES=lib -DCMAKE_FIND_LIBRARY_SUFFIXES=.a

make release #or just "make"...if a debug version of dealii is 
             #installed, make release avoids it

Then, after editing config.yaml, run the code with, e.g.,

mpirun -np 12 QuasistaticBrownianThermalNoise.cpp \
    --configuration=/path/to/config.yaml --configuration_multloss=/path/to/config_multloss.yaml

Example configuration files are in tests/InputFiles/ (cf. "Choosing the Physics" below).

You can run automated tests (currently, just black-box tests) by running ctest --output-on-failure after compiling.

To run on a cluster, you might use a batch submission script; an example script is provided.

CHOOSING THE PHYSICS

Many changes to the physics (materials, sizes, temperature, etc.) and numerical settings (e.g. choices affecting resolution) can be made by editing the input file config.yaml. Comments in the file explain each setting.

QuasistaticBrownianThermalNoise_Paper.cpp

For completeness, this is the version of the code used in https://dcc.ligo.org/LIGO-P1700183. This version is not as polished but gives equivalent results.

Testing

A sample output is ExampleEnergy.dat. Build and run QuasistaticBrownianThermalNoise.cpp without changing any code, and this should be your output.

QUESTIONS

Please send questions to glovelace at fullerton dot edu.