Troubleshooting

OpenQP Cannot Find Runtime Files

For normal installs, run:

pip install .

from the repository root, or install the package from PyPI. The installed package should locate its native library and data files without OPENQP_ROOT. Only set OPENQP_ROOT for custom layouts where Python is separated from the OpenQP runtime tree.

BLAS/LAPACK Integer ABI

OpenQP is ILP64-only: one 8-byte BLAS/LAPACK integer model on every platform. LP64 support was removed, and -DLINALG_LIB_INT64=OFF now fails the configure deliberately, so a stale CMake cache or an old script cannot produce a mixed-width build. Clear the cache and drop the flag.

Use ILP64 OpenBLAS or MKL on Linux, MKL ILP64 on Windows, and Accelerate's $NEWLAPACK$ILP64 interface on macOS 13.3 or newer.

SCF Does Not Converge

Try, in increasing order of intervention:

rhf/6-31g* scf(diis_type=vdiis)
geom="molecule.xyz"

rhf/6-31g* scf(converger_type=soscf)
geom="molecule.xyz"

rhf/6-31g* scf(converger_type=trah)
geom="molecule.xyz"

For difficult cases, use alternative_scf=trah, escalation=soscf,trah, MOM, or pFON as appropriate. TRAH cannot be used with mom=true or rstctmo=true: for those calculations use diis or soscf, and TRAH is left out of the escalation ladder.

Too Many Threads

Use either:

openqp input.oqp --omp 16

or:

rhf/6-31g* omp_threads=16
geom="molecule.xyz"

This controls OpenMP threads per process or MPI rank. MPI rank count remains controlled by the launcher, for example mpirun -np 4.

PCM Input Runs as Vacuum

PCM-enabled runs should fail clearly if the ddX runtime path is unavailable. Use:

rhf/6-31g* pcm
geom="molecule.xyz"

and keep the run type at energy for the current production PCM path.

MP2 Stops at the Build Guard

The default mp2.transform=auto selects a packed AO-to-MO transformation when the direct pair-build count exceeds OQP_MP2_MAX_JBUILDS. If the packed transformation fails, the direct fallback is still subject to that guard. Explicit transform=direct stops when the pair-build count exceeds the guard; use auto or n5 to select a packed transformation instead. Explicit n5 requires a packed form and stops if neither full nor occupied-virtual storage can fit or allocate. Reduce the basis/problem size when packed storage is unavailable; raise the direct-build guard only after checking runtime and memory cost. See MP2 transformation selection.

Documentation Looks Stale

The keyword reference should be checked against the OpenQP source schema:

• pyoqp/oqp/molecule/oqpdata.py
• pyoqp/oqp/utils/input_checker.py

If the code changes a default, allowed value, or runtime scope, update the matching keyword and workflow page in the documentation repository before the next release.