Getting and building QMCPACK

Obtain the latest release or development copy from http://www.qmcpack.org

Prerequisites

• C/C++ compilers
• CMake, build utility, http://www.cmake.org
• BLAS/LAPACK, numerical library, use platform-optimized libraries
• Libxml2, XML parser, http://xmlsoft.org/
• HDF5, portable I/O library, http://www.hdfgroup.org/HDF5/
• BOOST, peer-reviewed portable C++ source libraries, http://www.boost.org
• FFTW, FFT library, http://www.fftw.org/

Note that the einspline library is no longer required.

Building with CMake

The build system for QMCPACK is based on CMake. It will autoconfigure based on the detected compilers and libraries. Previously QMCPACK made extensive use of toolchains, but the system has since been updated to eliminate the use of toolchain files for most cases. The build system works with GNU, Intel, and IBM XLC compilers. Specific compile options can be specified either through specific environmental or CMake variables. When the libraries are installed in standard locations, e.g., /usr, /usr/local, there is no need to set environmental or cmake variables for the packages.

See the manual in manual/qmcpack_manual.pdf for build examples on Linux, Mac OS X etc.

Quick build

If you are feeling lucky and are on a standard UNIX-like system such as a Linux workstation:

• Safest quick build option is to specify the C and C++ compilers through their MPI wrappers. Here we use Intel MPI and Intel compilers. Move to the build directory, run cmake and make

cd build
cmake -DCMAKE_C_COMPILER=mpiicc -DCMAKE_CXX_COMPILER=mpiicpc ..
make -j 8

• Substitute mpicc and mpicxx or other wrapped compiler names to suit your system. e.g. With OpenMPI use

cd build
cmake -DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx ..
make -j 8

• If you are feeling particularly lucky, you can skip the compiler specification:

cd build
cmake ..
make -j 8

The complexities of modern computer hardware and software systems are such that you should check that the autoconfiguration system has made good choices and picked optimized libraries and compiler settings before doing significant production. i.e. Check the details below.

Set the environment

A number of enviornmental variables affect the build. In particular they can control the default paths for libraries, the default compilers, etc. The list of enviornmental variables is given below:

Environment variable	Description
CXX	C++ compiler
CC	C Compiler
MKL_ROOT	Path for MKL
LIBXML2_HOME	Path for libxml2
HDF5_ROOT	Path for HDF5
BOOST_ROOT	Path for Boost
FFTW_HOME	Path for FFTW

CMake options

In addition to reading the enviornmental variables, CMake provides a number of optional variables that can be set to control the build and configure steps. When passed to CMake, these variables will take precident over the enviornmental and default variables. To set them add -D FLAG=VALUE to the configure line between the cmake command and the path to the source directory.

• General build options

    CMAKE_C_COMPILER    Set the C compiler
    CMAKE_CXX_COMPILER  Set the C++ compiler
    CMAKE_BUILD_TYPE    A variable which controls the type of build (defaults to Release).
                        Possible values are:
                        None (Do not set debug/optmize flags, use CMAKE_C_FLAGS or CMAKE_CXX_FLAGS)
                        Debug (create a debug build)
                        Release (create a release/optimized build)
                        RelWithDebInfo (create a release/optimized build with debug info)
                        MinSizeRel (create an executable optimized for size)
    CMAKE_C_FLAGS       Set the C flags.  Note: to prevent default debug/release flags
                        from being used, set the CMAKE_BUILD_TYPE=None
                        Also supported: CMAKE_C_FLAGS_DEBUG, CMAKE_C_FLAGS_RELEASE,
                                        CMAKE_C_FLAGS_RELWITHDEBINFO
    CMAKE_CXX_FLAGS     Set the C++ flags.  Note: to prevent default debug/release flags
                        from being used, set the CMAKE_BUILD_TYPE=None
                        Also supported: CMAKE_CXX_FLAGS_DEBUG, CMAKE_CXX_FLAGS_RELEASE,
                                        CMAKE_CXX_FLAGS_RELWITHDEBINFO

• Key QMC build options

     QMC_CUDA            Enable CUDA and GPU acceleration (1:yes, 0:no)
     QMC_COMPLEX         Build the complex (general twist/k-point) version (1:yes, 0:no)
     QMC_MIXED_PRECISION Build the mixed precision (mixing double/float) version
                         (1:yes (GPU default), 0:no (CPU default)).
                         The CPU support is experimental.
                         Use float and double for base and full precision.
                         The GPU support is quite mature.
                         Use always double for host side base and full precision
                         and use float and double for CUDA base and full precision.
     ENABLE_TIMERS       Enable fine-grained timers (1:yes, 0:no (default)).
                         Timers are off by default to avoid potential slowdown in small
                         systems. For large systems (100+ electrons) there is no risk.
     ENABLE_SOA          (Experimental) Enable CPU optimization based on Structure-
                         of-Array (SoA) datatypes (1:yes, 0:no (default)). ```

• Additional QMC options

     QMC_INCLUDE         Add extra include paths
     QMC_EXTRA_LIBS      Add extra link libraries
     QMC_BUILD_STATIC    Add -static flags to build
     QMC_DATA            Specify data directory for QMCPACK performance and integration tests
     QE_BIN              Location of Quantum Espresso binaries including pw2qmcpack.x

• libxml2 related

     Libxml2_INCLUDE_DIRS  Specify include directories for libxml2
     Libxml2_LIBRARY_DIRS  Specify library directories for libxml2

• HDF5 related

     ENABLE_PHDF5        1(default)/0, enables/disable parallel collective IO.

• FFTW related

     FFTW_INCLUDE_DIRS   Specify include directories for FFTW
     FFTW_LIBRARY_DIRS   Specify library directories for FFTW

Example configure and build

In the build directory, run cmake with appropriate options, then make.

• Using Intel compilers and their MPI wrappers. Assumes HDF5 and libxml2 will be automatically detected.

cd build
cmake -DCMAKE_C_COMPILER=mpiicc -DCMAKE_CXX_COMPILER=mpiicpc ..
make -j 8

Special notes

It is recommended to create a helper script that contains the configure line for CMake. This is particularly useful when using environmental variables, packages are installed in custom locations, or the configure line may be long or complex. In this case it is recommended to add "rm -rf CMake*" before the configure line to remove existing CMake configure files to ensure a fresh configure each time that the script is called. and example script build.sh is given below:

export CXX=mpic++
export CC=mpicc
export ACML_HOME=/opt/acml-5.3.1/gfortran64
export HDF5_ROOT=/opt/hdf5
export BOOST_ROOT=/opt/boost

rm -rf CMake*

cmake                                               \
  -D CMAKE_BUILD_TYPE=Debug                         \
  -D Libxml2_INCLUDE_DIRS=/usr/include/libxml2      \
  -D Libxml2_LIBRARY_DIRS=/usr/lib/x86_64-linux-gnu \
  -D FFTW_INCLUDE_DIRS=/usr/include                 \
  -D FFTW_LIBRARY_DIRS=/usr/lib/x86_64-linux-gnu    \
  -D QMC_EXTRA_LIBS="-ldl ${ACML_HOME}/lib/libacml.a -lgfortran" \
  -D QMC_DATA=/projects/QMCPACK/qmc-data            \
  ..

Additional examples:

QMCPACK includes validation tests to ensure the correctness of the code, compilers, tools, and runtime. The tests should ideally be run each compilation, and certainly before any research use. The tests check the output against known mean-field, quantum chemistry, and other QMC results.

Set compile flags manually:

   cmake                                                \
      -D CMAKE_BUILD_TYPE=None                          \
      -D CMAKE_C_COMPILER=mpicc                         \
      -D CMAKE_CXX_COMPILER=mpic++                      \
      -D CMAKE_C_FLAGS="  -O3 -fopenmp -malign-double -fomit-frame-pointer -finline-limit=1000 -fstrict-aliasing -funroll-all-loops -Wno-deprecated -march=native -mtune=native" \
      -D CMAKE_CXX_FLAGS="-O3 -fopenmp -malign-double -fomit-frame-pointer -finline-limit=1000 -fstrict-aliasing -funroll-all-loops -Wno-deprecated -march=native -mtune=native" \
      ..

Add extra include directories:

   cmake                                                \
      -D CMAKE_BUILD_TYPE=Release                       \
      -D CMAKE_C_COMPILER=mpicc                         \
      -D CMAKE_CXX_COMPILER=mpic++                      \
      -D QMC_INCLUDE="~/path1;~/path2"                  \
      ..

Testing and validation of QMCPACK

For more informaton, consult QMCPACK pages at http://www.qmcpack.org and the manual. The tests currently use up to 16 cores in various combinations of MPI tasks and OpenMP threads.

Note that due to the small electron and walker counts used in the tests, they should not be used for any performance measurements. These should be made on problem sizes that are representative of actual research calculations.

Run the short (quick) tests

From the build directory, invoke ctest specifying only tests including "short" should be run

ctest -R short

These tests currently take several minutes to run. All tests should pass.

Run the long verification tests

For greater surety, the long verification tests use a far greater number of statistical samples than the "short" tests. These take several hours each to run.

From the build directory, invoke ctest with an increased test timeout

ctest --timeout 36000

This will run all the defined tests, "short" and "long" as well as the unit and other tests. If you are running on a system such as a large shared supercomputer you will likely have to run these tests from inside a submitted job to avoid run length limits.

Run individual tests

Individual tests can be run by specifying their name

ctest -R name-of-test-to-run

Documentation and support

For more informaton, consult QMCPACK pages at http://www.qmcpack.org, the manual PDF at https://docs.qmcpack.org/qmcpack_manual.pdf, or its sources in the manual directory.

If you have trouble using or building QMCPACK, or have questions about its use, please post to the Google QMCPACK group or contact a developer.

Contributing

Contributions of any size are very welcome. Guidance for contributing to QMCPACK is included in Chapter 1 of the manual https://docs.qmcpack.org/qmcpack_manual.pdf . We use a git flow model including pull request reviews. A continuous integration system runs on pull requests. See https://github.com/QMCPACK/qmcpack/wiki for details. For an extensive contribution, it can be helpful to discuss on the Google QMCPACK group, to create a GitHub issue, or to talk directly with a developer.

Contributions are made under the same UIUC/NCSA open source license that covers QMCPACK. Please contact us if this is problematic.