Hanging MPI processes when writing MMN and WANPROJ files

[benoit]

Dear VASP developers,

I noticed that MMN and WANPROJ files are written by all MPI ranks, when trying to generate the maximally localized wannier functions using Wannier90 interface using VASP 6.2.1. This may cause MPI processes to hang depending on the file system. I experienced this behavior on a supercomputer using IBM Spectrum Scale parallel file system (ex-GPFS) while the same job completes successfully on another supercomputer using NFS file system.

I guess that writing of MMN and WANPROJ files should probably be carried out by MPI rank 0 only. The attached patch file allowed me to fix this issue in VASP 6.2.1.

Kind regards,

Benoit

[martin.schlipf]

Thank you Benoit for bringing this to our attention. The patch you provide looks great, much appreciated.