MPI enabled builds

[awvwgk]

• I read the conda-forge documentation and could not find the solution for my problem there.

Issue:
Currently looking into building DFTB+ on conda-forge with plumed support, I think we would need an MPI enabled version as well to build all variants of the package with plumed support. Are there plans to support MPI in this package as well?

cc @conda-forge/dftbplus

[GiovanniBussi]

@awvwgk thanks for raising this. Currently we have no plan in this sense. I noticed that unfortunately preparing a package that works both with and without MPI is non trivial, and I thus didn't have time to figure out how to fix our recipe. If you know how to do it, could you please make a pull request in this sense? Ideally:

• default should be no MPI
• optionally the user might install MPI support

Thanks!

[awvwgk]

Will give it a try in #21, let's see how this goes.

There is probably more work to do than adding MPI to the build matrix. Do any of the dependencies have to support MPI as well?

[GiovanniBussi]

There is probably more work to do than adding MPI to the build matrix. Do any of the dependencies have to support MPI as well?

Not that I know. I guess you are thinking about fftw? We only use the serial version.

[GiovanniBussi]

Will give it a try in #21, let's see how this goes.

🤞

[awvwgk]

Seems like it works with MPICH, but fails with OpenMPI. Not sure what the cause it, but maybe it seems to be an issue with the compiler wrappers (we don't use those in DFTB+).

[awvwgk]

Feel free to close this PR or keep it open to track the build failure on OSX-ARM with OpenMPI.