Frequently Asked Questions


What is the oldxml?

The old format (-D__OLDXML) has been deprecated since version 6.4. oldxml allows you to read the output (wavefunctions, etc) from an old XML file.

How do I know when I need oldxml?

For newer version QE (>6.3), the XML file name is data-file-schema.xml. In contrast, the XML file name is data-file.xml for older version QE (some with precompiler flag -D__OLDXML)


Some Intel MPI/MKL errors occur. What do I do?


export LD_PRELOAD=/opt/intel/mkl/lib/intel64/

Why can’t I read the wavefunctions? Why does it hang?

  • If the wavefunctions were stored by old version QE (<6.4) or eQE, please try reinstall the QEpy with oldxml=yes.

  • There are two different ways to store wavefunctions in QE, which is controls by PW parameter wf_collect. In doubt, simply use one processor to read.

Some f90wrap errors occur. What do I do?

  • No module named f90wrap.__main__...

Please try install the latest f90wrap . e.g.

python -m pip install --upgrade f90wrap

Signal: Segmentation fault...

  • QEpy and mpi4py should installed with same compiler. If not, try reinstall the mpi4py by:

    python -m pip install mpi4py --no-cache-dir



For new version of gcc (eg. gcc=11.2) with LTO supported or under conda environment, if you met the problem when you install the QEpy:

  • lto1: fatal error:...

Try disable link-time-optimization by add -fno-lto to the variable FFLAGS and CFLAGS.


  1. For gfortran>=10.0 sometimes still works, but will has error:

    • Type mismatch between actual argument...

    Try to add -fallow-argument-mismatch to the variable FFLAGS (e.g. FFLAGS='-fPIC -fallow-argument-mismatch').

  2. For some versions of the MacOS, maybe you will has error:

    • Illegal Instruction: 4...

    Try to add -mmacosx-version-min=10.14 to the FFLAGS.

  3. For a few versions of BLAS library, will raise error:

    • Segmentation fault - invalid memory reference...

    This is due to the zdotc function of external libraries. More details to here. One solution is manually append the -Dzdotc=zdotc_wrapper to DFLAGS or MANUAL_DFLAGS in of QE. You also can do it during make:

make pw MANUAL_DFLAGS='-Dzdotc=zdotc_wrapper'

Intel Compiler

  1. If you met any problems like the following, please try a newer Intel compiler or GNU compiler.

    • [MPID_nem_tmi_pending_ssend_dequeue]: ERROR: can not find matching ssend...

    • The initial density totally wrong with more than one nodes.

  2. The gcc version between 4.8-9.2 are supported by intel compiler, which upgraded until 2022.1 version. More details to here.

    • ...error: attribute "__malloc__" does not take arguments...


If you met some problems like the following:

  • mca_base_component_repository_open: unable to open mca_patcher_overwrite...

Please update to latest version of OpenMPI, or fix with patchelf (openmpi=2.1.1):

for filename in $(ls $prefix/lib/openmpi/*.so); do
    patchelf --add-needed $filename
    patchelf --set-rpath "\$ORIGIN/.." $filename