Installation¶

Recommended Install¶

Use the Python package when possible:

pip install openqp

For a local source checkout:

git clone https://github.com/Open-Quantum-Platform/openqp.git
cd openqp
pip install .

The top-level package build installs the Python package, native library, header files, and data files together. Normal command-line use does not require OPENQP_ROOT after installation.

Requirements¶

Python 3.9 or newer
GCC, G++, and Gfortran
CMake 3.25 or newer
BLAS/LAPACK
cffi, NumPy, SciPy, and geomeTRIC
Ninja, recommended for source builds
OpenMPI or another MPI implementation, only when building with MPI

See the Build Options reference for the full CMake option table, defaults, BLAS/LAPACK choices, external dependency cache behavior, and package-build overrides.

Source Build¶

The default source install is:

pip install .

For development builds where you want to inspect the native build directory:

cmake -B build -G Ninja \
  -DCMAKE_C_COMPILER=gcc \
  -DCMAKE_CXX_COMPILER=g++ \
  -DCMAKE_Fortran_COMPILER=gfortran \
  -DCMAKE_INSTALL_PREFIX=. \
  -DENABLE_OPENMP=ON
ninja -C build install
cd pyoqp
pip install .

On macOS, prefer Homebrew GCC and the native Accelerate BLAS/LAPACK stack:

cmake -B build -G Ninja \
  -DCMAKE_C_COMPILER=/opt/homebrew/bin/gcc-15 \
  -DCMAKE_CXX_COMPILER=/opt/homebrew/bin/g++-15 \
  -DCMAKE_Fortran_COMPILER=/opt/homebrew/bin/gfortran-15 \
  -DCMAKE_INSTALL_PREFIX=. \
  -DENABLE_OPENMP=ON \
  -DLINALG_LIB=auto \
  -DLINALG_LIB_INT64=OFF
ninja -C build install
cd pyoqp
pip install .

Adjust the compiler suffix to match the Homebrew GCC version installed on the machine.

Common CMake Options¶

Option	Default	Meaning
`-DENABLE_MPI=ON`	`OFF`	Enable MPI support. Use an MPI Fortran compiler wrapper such as `mpif90`.
`-DENABLE_OPENMP=ON`	`OFF` in CMake, `ON` for Python package builds	Enable OpenMP parallel sections.
`-DUSE_LIBINT=ON`	`ON` in CMake, `OFF` for Python package builds	Use Libint for ERIs instead of the native Rys path.
`-DLINALG_LIB=<vendor>`	`auto`	Select BLAS/LAPACK provider.
`-DLINALG_LIB_INT64=ON`	`ON`	Use ILP64 BLAS/LAPACK.
`-DENABLE_OPENTRAH=OFF`	`ON` in CMake, `OFF` for Python package builds	Skip the external OpenTrustRegion library and use native TRAH.
`-DOQP_REUSE_EXTERNALS=OFF`	`ON`	Disable reusable bundled-external build caches.

For the complete list, including ENABLE_DDX, BUILD_SHARED_LIBS, ENABLE_PYTHON, sanitizer flags, and external dependency cache paths, see Build Options.

ILP64 BLAS/LAPACK is the normal build mode. LP64 (-DLINALG_LIB_INT64=OFF) is supported only on macOS, mainly for a consistent native Accelerate build.

Runtime Files¶

Installed packages resolve runtime files package-locally first. Source-tree development layouts are also detected when the native library has been installed into the checkout. Keep OPENQP_ROOT only as a compatibility fallback for custom layouts where Python and the OpenQP runtime tree are separated.

OpenMP Threads¶

OpenQP accepts the OpenMP thread count from the command line:

openqp h2o.inp --omp 16

or from the input file:

[input]
omp_threads=16

Precedence is --omp, then [input] omp_threads, then OMP_NUM_THREADS, then the built-in default.

Test¶

openqp --run_tests all

For a smaller first check:

openqp examples/HF/H2O_RHF-HF_ENERGY.inp