Common errors

This guide lists frequent problems, their causes and solutions.

Summary table

Symptom	Likely cause	Solution
pw.x not found	QE not installed or not in PATH	pw.x not found
mpirun not found	MPI not installed	MPI
error while loading shared libraries	Missing FFTW/MPI libs	Libraries
Very slow runs	OpenMP + MPI misconfigured	MPI performance
No terminal plots	Missing plotext/matplotlib or stale cache	Missing plots
pw.x exit code 1 (Docker)	Incomplete QE in image	Docker
Identical energy between iterations	Stale QE output	Convergence
unknown chemical symbol	Invalid chemical formula	Invalid formula

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pw.x not found

Symptom:

ERROR: ❌ pw.x executable not found

Solutions:

python3 qe_runner.py input.in --qe-path /path/to/qe-7.0
export PATH="/path/to/qe-7.0/bin:$PATH"
python3 qe_runner.py input.in --pw /path/to/qe-7.0/bin/pw.x

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Invalid chemical formula

Symptom:

❌ Erreur: symbole chimique inconnu 'Bo' dans 'BBo'.

Cause: The string passed to fetcher.py or qe-bridge is not a valid chemical formula. Each segment must be a periodic-table element symbol (Si, C, Ge…).

Triggering example:

python3 fetcher.py BBo   # 'Bo' is not a valid element symbol

Solution: Check spelling and use only recognized element symbols:

python3 fetcher.py B     # Boron
python3 fetcher.py Si    # Silicon
python3 fetcher.py SiGe  # Silicon-germanium alloy

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MPI not found

Symptom:

WARNING: ⚠️  mpirun not found in PATH, running on single core

Solution:

sudo apt-get install -y libopenmpi-dev openmpi-bin

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Missing libraries

Symptom:

pw.x: error while loading shared libraries: libfftw3f.so.3: cannot open shared object file

Solution:

export LD_LIBRARY_PATH="/home/user/qe-7.0/lib:$LD_LIBRARY_PATH"

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MPI performance

export OMP_NUM_THREADS=1
python3 qe_runner.py input.in --nproc 4

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Missing plots

pip install plotext matplotlib
rm -rf __pycache__ *.pyc
python3 plotter.py epsilon_out/Si_epsr.dat

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Docker

If pw.x fails inside the container:

• Pull the latest image: docker pull lauryneelv/qe-to-tcad:latest
• Check mounted volume permissions: docker run -v "$PWD:/data" ...
• Pass --epsilon empiric (no Y/N prompt without -it)
• With sudo docker, pass the key explicitly: -e MP_API_KEY="your_key"
• On Mac Apple Silicon: add --platform linux/amd64 if the image does not start

Older images (< 0.2.7)

Since 0.2.7, OpenMPI allows mpirun as root in the image. Only use -e OMPI_ALLOW_RUN_AS_ROOT=1 when troubleshooting older images.

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Convergence

If energy is identical between iterations, delete stale files in out/ and rerun.

See also

• Installation
• Optimization