Error in `convert4qmc` with periodic PySCF calculation

**Describe the bug**
Running [02_diamond_hf_qmc](https://github.com/QMCPACK/qmcpack/blob/develop/nexus/nexus/examples/qmcpack/rsqmc_pyscf/02_diamond_hf_qmc/diamond_pp_hf_gamma.py) fails when running `convert4qmc`.

**To Reproduce**
Steps to reproduce the behavior:
1. Commit: e6f16189c7f34eb7702a2738358cdd7cecfca8db
2. CMake command (lines split for readability):
```console
/usr/bin/cmake
-DCMAKE_INSTALL_PREFIX=/home/brock/Documents/github/qmcpack/build
-DCMAKE_C_COMPILER=/usr/lib64/openmpi/bin/mpicc
-DCMAKE_CXX_COMPILER=/usr/lib64/openmpi/bin/mpiCC
-DCMAKE_BUILD_TYPE=DEBUG
-DQMC_MPI=1
-DPython3_EXECUTABLE=/home/brock/Documents/github/qmcpack/.venv/bin/python
-DQE_BIN=/home/brock/qe/build/bin
-DHDF5_PREFER_PARALLEL=TRUE
"-DHDF5_ROOT=/usr/lib64/openmpi/lib;/usr/lib64/gfortran/modules/openmpi;/usr/include/openmpi-x86_64"
-DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE
-S /home/brock/Documents/github/qmcpack
-B /home/brock/Documents/github/qmcpack/build/debug
-G Ninja
```
3. full program/test invocation command
```console
export OMP_NUM_THREADS=1
mpirun -np 1 convert4qmc -prefix c4q -hdf5 -nojastrow -orbitals scf.twistnum_000.h5
```

**Expected behavior**
Expect `convert4qmc` to run without error.

**System:**
Desktop, Fedora Linux 43 (KDE Plasma Desktop Edition)
AMD Ryzen 9 7900X (12 cores, 24 logical processors)
```
Python 3.14.5
uv 0.12.3
cif2cell 2.1.0
coverage 7.15.0
h5py 3.16.0
matplotlib 3.11.1
numpy 2.5.2
pycifrw 4.4.6
pydot 4.0.1
pytest 9.1.1
pytest-cov 7.1.0
pytest-order 1.5.0
scipy 1.18.0
seekpath 2.2.1
spglib 2.7.0
sphinx 9.1.0

CMake 3.31.11
hdf5.x86_64 1.14.6-6.fc43
fftw.x86_64 3.3.10-16.fc43
boost.x86_64 1.83.0-17.fc43
openblas.x86_64 0.3.29-2.fc43
OpenMPI 5.0.8
mpicc 15.3.1
mpiCC 15.3.1
Ninja 1.13.1
PySCF 2.14.0
Quantum ESPRESSO 7.5
```

**Additional context**
Here are the inputs and outputs for `convert4qmc`
[convert4qmc_output.tar.gz](https://github.com/user-attachments/files/31044195/convert4qmc_output.tar.gz)

Start by running the reported convert4qmc command at commit e6f16189c7f34eb7702a2738358cdd7cecfca8db with the 02_diamond_hf_qmc/diamond_pp_hf_gamma.py inputs. Inspect convert4qmc_output.tar.gz to identify the actual failure, then compare it with the expected successful conversion. Done means the periodic PySCF example converts without error.

Written by the indexing model from the issue text.