Cloning ChASE source code

ChASE is an open source project and it is available on GitHub. In order to download the source code of ChASE one needs to have the git utility installed. To clone a local copy of the ChASE repository execute the command:

git clone https://github.com/ChASE-library/ChASE

Building and Installing the ChASE library

On a Linux system with MPI and CMake installed in the standard locations, ChASE can be build by executing in order the following commands (after having cloned the repository):

cd ChASE/
mkdir build
cd build/
cmake .. -DCMAKE_INSTALL_PREFIX=${ChASEROOT}
make install

In the commands above, the variable ${CHASEROOT} is the path to install ChASE on user’s laptops. CMake will auto-detect the dependencies and select the default installed modules. In order to select a specific module installation, one can manually specify several build options, especially when multiple versions of libraries or several different compilers are available on the system. For instance, any C++, C, or Fortran compiler can be selected by setting the CMAKE_CXX_COMPILER, CMAKE_C_COMPILER, and CMAKE_Fortran_COMPILER variables, respectively. The following provide an illustration of such setting.

-D CMAKE_CXX_COMPILER=/usr/bin/g++ \
-D CMAKE_C_COMPILER=/usr/bin/gcc   \
-D CMAKE_Fortran_COMPILER=/usr/bin/gfortran

Analogously, it may be necessary to manually specify the paths to the MPI implementation by, for example, setting the following variables.

-D MPI_CXX_COMPILER=/usr/bin/mpicxx \
-D MPI_C_COMPILER=/usr/bin/mpicc \
-D MPI_Fortran_COMPILER=/usr/bin/mpif90

For instance, installing ChASE on an Apple computer with gcc and Accelerate, one could execute the following command:

cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_C_COMPILER=gcc -DCMAKE_Fortran_COMPILER=gfortran ..

Quick Hands-on by Examples

For a quick test and usage of the library, we provide various ready-to-use examples which use ChASE to solve eigenproblems. Some of these examples make the additional use of the C++ library Boost for the parsing of command line values. Thus Boost should also be provided before the installation of ChASE if users would like to build ChASE with these examples. In order to build these examples together with ChASE the sequence of building commands should be slightly modified as below:

cd ChASE/
mkdir build
cd build/
cmake .. -DCMAKE_INSTALL_PREFIX=${ChASEROOT} -DBUILD_WITH_EXAMPLES=ON
make install

Executing ChASE using the ready-to-use examples is rather straightforward. For instance, 0. Hello World is executed by simply typing the line below:

./0_hello_world/0_hello_world

In this example, a Clement matrix is generated and default values of parameters are used.

To run this example with MPI, start the command with the mpi launcher of your choice, e.g. mpirun or srun.

For sake of completeness we provide a complete list of parameters in this example below.

Parameter (default value)	Description
N (=1001)	Size of the Input Matrix
nev (=40)	Wanted Number of Eigenpairs
nex (=20)	Extra Search Dimensions
deg (=20)	Initial filtering degree, value set by config.SetDeg(20)
tol (=1e-10)	Minimum tolerance required to declare eigenpairs converged, value set by config.SetTol(1e-10)
opt (=true)	If optimize the degree of filter internally by ChASE, value set by config.SetOpt(true)

Note

For the quick test and benchmark, user can modify some of parameters, e.g., to change the size of matrix N which will generate a clement matrix of different size, to change the number of wanted eigepairs nev, etc.

Note

For the fine tuning of more parameters in ChASE, please visit Configuration, in which we provide a class to set up all the parameters of eigensolvers. For the suggestion of selecting values of parameters, please visit Parameters and Configurations.

Note

For a complete explanation of all the examples, please visit Examples.