# Gmx\_mpi using multi-core

**URL:** <https://gromacs.bioexcel.eu/t/gmx-mpi-using-multi-core/6134>\
**Category:** User discussions\
**Created:** [April 7, 2023, 8:12am UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-using-multi-core/6134 "2023-04-07T08:12:21Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![rainbow](https://avatars.discourse-cdn.com/v4/letter/r/7993a0/32.png) [@rainbow](https://gromacs.bioexcel.eu/u/rainbow)\
**Post date:** [April 7, 2023, 8:12am UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-using-multi-core/6134/1 "2023-04-07T08:12:21Z")

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GROMACS version: 2022.5  
GROMACS modification: No

Dear gmx users,

Can I use multi-core when analyzing using gmx\_mpi?  
Does it only apply when using gmx\_mpi mdrun?

For example, gmx\_mpi cluster or gmx\_mpi rms, etc.  
When I tried it, it only uses one core.

Thanks for your help.

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<div class="post-metadata">

**Author:** ![al42and](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/al42and/32/1393_2.png) [@al42and](https://gromacs.bioexcel.eu/u/al42and)\
**Post date:** [April 13, 2023, 4:20pm UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-using-multi-core/6134/2 "2023-04-13T16:20:30Z")

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Hi!

Only `gmx mdrun` can run with multiple MPI ranks.

Some analysis tools can take advantage of OpenMP parallelism. But `gmx cluster` and `gmx rms` are single-thread only.