[QE-users] [QE-GPU] [PHonon] Runtime Crash in ph.x (v7.5 OpenACC) during Electron-Phonon Calculation (elphon.f90)

[Paolo Giannozzi]

I don't think that the electron-phonon calculation has been ported to GPUs

Paolo


On 11/25/25 06:52, Dolon Pal via users wrote:
> Dear Quantum ESPRESSO Developers and Community,
> 
> I am writing to report a persistent runtime error in the GPU-accelerated 
> version of |ph.x| (Quantum ESPRESSO v7.5) when calculating electron- 
> phonon coefficients using the OpenACC port.
> 
> While the code successfully calculates the Dynamical Matrices and 
> Frequencies on the GPU, it consistently crashes during the final 
> electron-phonon interaction step (routine |elphon|) with a File I/O 
> error, specifically related to the temporary file |a2Fsave|.
> 
> *1. System and Compilation Details:*
> 
>   *
> 
>     *Version:* Quantum ESPRESSO v7.5 (GitLab release)
> 
>   *
> 
>     *Compiler:* NVIDIA HPC SDK v24.9
> 
>   *
> 
>     *Configuration:* |./configure --enable-openacc --with-cuda=yes --
>     with-cuda-cc=89 --with-cuda-runtime=12.6|
> 
>   *
> 
>     *Hardware:* NVIDIA RTX 4090 (Ada Lovelace)
> 
>   *
> 
>     *MPI:* OpenMPI (via NVIDIA HPC SDK)
> 
> *2. The Issue:* When running |ph.x| with |electron_phonon = 
> 'interpolated'| (or any mode that triggers |elphon|), the execution 
> aborts immediately after diagonalizing the dynamical matrix for the 
> first q-point. The crash occurs regardless of the MPI parallelization 
> level (reproduced with both |-np 1| and |-np 8|).
> 
> *3. Error Log:* The crash points to a read error in |elphon.f90| 
>   attempting to read a file that appears to be empty or not flushed to disk.
> 
>     |FIO-F-217/list-directed read/unit=40/attempt to read past end of
>     file. File name = './out/mgb2.a2Fsave', formatted, sequential access
>     record = 1 In source file /path/to/q-e/PHonon/PH/elphon.f90, at line
>     number 847 |
> 
> |File name = './out/mgb2.a2Fsave', formatted, sequential access record = 
> 1 In source file /path/to/q-e/PHonon/PH/elphon.f90, at line number 847 |
> 
> *4. Reproduction Case (MgB2):* I reproduced this using a standard MgB2 
> test case.
> 
> /Input snippet (|ph.in|):/
> 
> Fortran
> 
> |&INPUTPH tr2_ph = 1.0d-14, prefix = 'mgb2', outdir = './out', fildyn = 
> 'mgb2.dyn', fildvscf = 'mgb2.dvscf', electron_phonon = 'interpolated', ! 
> <--- Triggers the crash trans = .true., ldisp = .true., nq1=6, nq2=6, 
> nq3=4 / |
> 
> *5. Observations:*
> 
>  1.
> 
>     *Pure Phonons work:* If I comment out |electron_phonon|, the GPU run
>     finishes successfully and writes |.dyn| and |.dvscf|files.
> 
>  2.
> 
>     *CPU Works:* The exact same input runs successfully on the CPU-only
>     binary (gfortran compilation).
> 
>  3.
> 
>     *File Incompatibility:* I attempted to run the heavy phonon
>     calculation on the GPU and the final electron-phonon collection on
>     the CPU (using |recover=.true.| or |trans=.false.|), but the CPU
>     binary cannot read the GPU-generated |.dvscf|/binary files
>     ("problems reading u" error), likely due to binary format/padding
>     differences between |nvfortran|and |gfortran|.
> 
> It appears there is a race condition or file handling issue in the 
> OpenACC implementation of the |elphon| routine where the |a2Fsave| file 
> is read before it is successfully written/closed.
> 
> Any advice on a workaround or a patch for |elphon.f90| to stabilize the 
> GPU I/O would be greatly appreciated.
> 
> Thank you for your time and for developing this software.
> 
> Best regards,
> 
> Dholon Kumar Paul
> 
> Research Assistant, BRAC University, Bangladesh
> 
> 
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216