# Gmx\_mpi doesn't run

**URL:** <https://gromacs.bioexcel.eu/t/gmx-mpi-doesnt-run/633>\
**Category:** User discussions\
**Created:** [August 7, 2020, 5:49am UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-doesnt-run/633 "2020-08-07T05:49:24Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![novalex](https://avatars.discourse-cdn.com/v4/letter/n/6f9a4e/32.png) [@novalex](https://gromacs.bioexcel.eu/u/novalex)\
**Post date:** [August 7, 2020, 5:49am UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-doesnt-run/633/1 "2020-08-07T05:49:24Z")

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GROMACS version: 2020.3  
GROMACS modification: No  
I have installed GROMACS and then built mdrun only to have mpi support. I am following the instructions here [http://manual.gromacs.org/documentation/current/install-guide/index.html](http://manual.gromacs.org/documentation/current/install-guide/index.html) without modification. However, after I’ve compiled and installed everything, and checked that all my tests have passed, I still cannot get gmx\_mpi to run. The following error shows up:

 ![CannotFindGMX_MPI](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/1X/61ea3e2aefd16c32f941fa65316cc13f8730b76d.png)

Why does it say “error on file gmx\_mpi (no such file or directory)”?

Any help would be greatly appreciated

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**Author:** ![JohnWhittaker](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/johnwhittaker/32/126_2.png) [@JohnWhittaker](https://gromacs.bioexcel.eu/u/JohnWhittaker)\
**Post date:** [August 7, 2020, 10:39am UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-doesnt-run/633/2 "2020-08-07T10:39:40Z")

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You have to tell the computer where to look for the “gmx\_mpi” binary before you can use it.

It seems you are skipping the “source” step at the bottom of the “quick and dirty installation” section from the link you posted.

Try: “source /path/to/gromacs/install/bin/GMXRC” without quotes and replace the path with where you installed the gromacs binaries. The default location is /usr/local/gromacs/

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**Author:** ![JohnWhittaker](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/johnwhittaker/32/126_2.png) [@JohnWhittaker](https://gromacs.bioexcel.eu/u/JohnWhittaker)\
**Post date:** [August 7, 2020, 10:47am UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-doesnt-run/633/3 "2020-08-07T10:47:08Z")

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Forgot to mention - since you installed an mdrun-only version of GROMACS, the binary you will use to launch mdrun will not be “gmx\_mpi mdrun” but instead “mdrun\_mpi” (if you didn’t mess with the default suffixes).

See the “Quick and dirty cluster installation” section in the link you posted.

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**Author:** ![novalex](https://avatars.discourse-cdn.com/v4/letter/n/6f9a4e/32.png) [@novalex](https://gromacs.bioexcel.eu/u/novalex)\
**Post date:** [August 7, 2020, 10:14pm UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-doesnt-run/633/4 "2020-08-07T22:14:36Z")

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I did source GMXRC and gmx runs, just not gmx\_mpi. I didn’t alter the default suffixes. I haven’t tried “mdrun\_mpi” yet, so I’ll try that and let you know how it goes!

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<div class="post-metadata">

**Author:** ![novalex](https://avatars.discourse-cdn.com/v4/letter/n/6f9a4e/32.png) [@novalex](https://gromacs.bioexcel.eu/u/novalex)\
**Post date:** [August 9, 2020, 10:24pm UTC](https://gromacs.bioexcel.eu/t/gmx-mpi-doesnt-run/633/5 "2020-08-09T22:24:31Z")

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mdrun\_mpi ran! Thank you! Still a lot that I need to figure out about running on multiple nodes but at least I’m running