Build Options

This page lists the OpenQP CMake options exposed by the source tree. It is meant for source builds, package maintainers, and developers who need to tune native dependencies.

Most users should install OpenQP with:

pip install openqp

For source checkouts, the top-level Python package build uses scikit-build and passes a few CMake overrides from pyproject.toml. A direct CMake build uses the defaults in CMakeLists.txt.

Passing Options

For direct CMake builds:

cmake -B build -G Ninja \
  -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_INSTALL_PREFIX=. \
  -DENABLE_OPENMP=ON \
  -DLINALG_LIB=auto
ninja -C build install

For pip install ., pass CMake options with CMAKE_ARGS:

CMAKE_ARGS="-DENABLE_MPI=ON -DLINALG_LIB=OpenBLAS" pip install .

The package build already sets several defaults for ordinary command-line use; see Python Package Build Defaults.

Core Options

Option	Direct CMake default	Python package default	Values	Use
CMAKE_BUILD_TYPE	Release	Release	Release, Debug, RelWithDebInfo	Select optimization and debug flags for single-configuration generators such as Ninja.
CMAKE_INSTALL_PREFIX	CMake default	.	Path	Install root for lib, include, and share runtime files. Package builds install into the wheel layout.
CMAKE_C_COMPILER	Auto	Auto	Compiler path	C compiler. Set with matching C++, Fortran compilers for reproducible builds.
CMAKE_CXX_COMPILER	Auto	Auto	Compiler path	C++ compiler, required for C++ wrappers and Libint verification.
CMAKE_Fortran_COMPILER	Auto	Auto	Compiler path	Fortran compiler. Use an MPI wrapper when building with MPI.
BUILD_SHARED_LIBS	ON	ON	ON, OFF	Build shared libraries when ON; OFF forces static-library lookup and static executable link flags for GNU.
BUILD_TESTING	ON	ON	ON, OFF	Enable CTest targets and optional smoke tests.
ENABLE_PYTHON	ON	ON	ON, OFF	Build the Python CFFI extension and install Python runtime files.
ENABLE_OPENMP	OFF	ON	ON, OFF	Enable OpenMP parallel kernels.
ENABLE_MPI	OFF	OFF	ON, OFF	Enable MPI support. Requires MPI and usually MPI compiler wrappers.

Integral, Optimizer, and Solvent Backends

Option	Direct CMake default	Python package default	Values	Use
USE_LIBINT	ON	OFF	ON, OFF	Build and use the external Libint two-electron integral path. OFF uses OpenQP's native Rys path.
ENABLE_OPENTRAH	ON	OFF	ON, OFF	Build and link the external OpenTrustRegion solver. OFF drops otr_interface.F90 and uses native TRAH fallback behavior.
ENABLE_DDX	OFF	OFF	ON, OFF	Enable the optional ddX continuum-solvation backend.
DDX_ROOT	Unset	Unset	Path or environment variable	When ENABLE_DDX=ON, use a prebuilt ddX install. If unset, OpenQP builds ddX v0.8.0 with matching BLAS integer width.

BLAS and LAPACK

Option	Default	Values	Use
LINALG_LIB	auto	auto, netlib, FLAME, Intel10_64ilp, Intel10_64ilp_seq, Intel10_64_dyn, OpenBLAS	Select the BLAS/LAPACK provider.
LINALG_LIB_INT64	ON	ON, OFF	Use the 64-bit BLAS/LAPACK integer interface when ON.
CMAKE_FIND_ROOT_PATH_MODE_PACKAGE	CMake default	BOTH, ONLY, NEVER	Useful for wheel/cross builds where CMake must search both host and package roots.

LINALG_LIB=auto first tries a system BLAS/LAPACK. If nothing suitable is found, OpenQP falls back to the bundled NetLib build. LINALG_LIB=none is listed internally but rejected because OpenQP and OpenTrustRegion require BLAS/LAPACK.

The default build expects ILP64 BLAS/LAPACK:

cmake -B build -G Ninja -DLINALG_LIB_INT64=ON

LP64 builds:

cmake -B build -G Ninja -DLINALG_LIB_INT64=OFF

are supported only on macOS, primarily for native Accelerate builds. On Linux, use ILP64 OpenBLAS, MKL, or the bundled NetLib fallback.

External Dependency Cache

OpenQP builds several bundled external dependencies when needed, including Libint, NLopt, Libxc, tagarray, libecpint, NetLib LAPACK/BLAS, OpenTrustRegion, fprettify, and ddX.

Option	Default	Values	Use
OQP_REUSE_EXTERNALS	ON	ON, OFF	Reuse bundled external builds across fresh OpenQP build directories.
OQP_EXTERNALS_ROOT	Platform cache path	Path	Override the reusable external dependency cache root.
OQP_EXTERNAL_ROOT	Unset	Path	Backward-compatible alias for OQP_EXTERNALS_ROOT.
OQP_LIBXC_C_FLAGS_RELEASE	Empty	Compiler flags	Advanced: extra release C flags passed only to the external Libxc build.

Default cache roots are:

Platform	Default cache root
macOS	~/Library/Caches/openqp/externals
Linux with XDG_CACHE_HOME	$XDG_CACHE_HOME/openqp/externals
Linux with HOME	~/.cache/openqp/externals
Fallback	<build>/external-cache

Disable reuse when debugging dependency rebuilds:

cmake -B build -G Ninja -DOQP_REUSE_EXTERNALS=OFF

Use a shared cache location on a build machine:

cmake -B build -G Ninja -DOQP_EXTERNALS_ROOT=/opt/openqp-cache/externals

Developer and Diagnostic Options

Option	Default	Values	Use
ENABLE_ASAN	OFF	ON, OFF	Enable AddressSanitizer flags for GNU builds.
ENABLE_LSAN	OFF	ON, OFF	Enable LeakSanitizer flags for GNU builds.
ENABLE_UBSAN	OFF	ON, OFF	Enable UndefinedBehaviorSanitizer flags for GNU builds.
ENABLE_TSAN	OFF	ON, OFF	Enable ThreadSanitizer flags for GNU builds.
ENABLE_MSAN	OFF	ON, OFF	Declared but not currently used.
ENABLE_Formatter	ON	ON, OFF	Add the Fortran formatting target using fprettify.

Example debug build with runtime checks:

cmake -B build-debug -G Ninja \
  -DCMAKE_BUILD_TYPE=Debug \
  -DENABLE_ASAN=ON \
  -DENABLE_UBSAN=ON
ninja -C build-debug

Python Package Build Defaults

The top-level pip install . build uses these CMake overrides from pyproject.toml:

CMake define	Package value	Reason
USE_LIBINT	OFF	Prefer the native Rys path for package builds.
ENABLE_OPENMP	ON	Enable parallel production kernels by default.
ENABLE_OPENTRAH	OFF	Avoid the external OpenTrustRegion dependency in ordinary package builds.
LINALG_LIB_INT64	ON	Build against ILP64 BLAS/LAPACK by default.
CMAKE_INSTALL_PREFIX	.	Keep native runtime files package-local.

Platform wheel builds add a few more environment-level settings:

Platform	Wheel build settings
Linux	LINALG_LIB=auto, LINALG_LIB_INT64=ON, CMAKE_FIND_ROOT_PATH_MODE_PACKAGE=BOTH
macOS	Homebrew GCC compilers, LINALG_LIB=auto, LINALG_LIB_INT64=OFF

Common Recipes

Linux development build:

cmake -B build -G Ninja \
  -DCMAKE_BUILD_TYPE=Debug \
  -DCMAKE_INSTALL_PREFIX=. \
  -DUSE_LIBINT=OFF \
  -DENABLE_OPENMP=ON \
  -DLINALG_LIB_INT64=ON
ninja -C build install

macOS Homebrew GCC build:

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

MPI build:

cmake -B build-mpi -G Ninja \
  -DCMAKE_C_COMPILER=mpicc \
  -DCMAKE_CXX_COMPILER=mpicxx \
  -DCMAKE_Fortran_COMPILER=mpif90 \
  -DENABLE_MPI=ON \
  -DENABLE_OPENMP=ON
ninja -C build-mpi install

ddX-enabled build:

cmake -B build-ddx -G Ninja \
  -DENABLE_DDX=ON \
  -DDDX_ROOT=/path/to/ddx/install
ninja -C build-ddx install

If DDX_ROOT is omitted, OpenQP builds the matching ddX dependency itself.