# External Potential Module for Pulling Simulations

**URL:** <https://gromacs.bioexcel.eu/t/external-potential-module-for-pulling-simulations/734>\
**Category:** User discussions\
**Created:** [August 30, 2020, 9:18am UTC](https://gromacs.bioexcel.eu/t/external-potential-module-for-pulling-simulations/734 "2020-08-30T09:18:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Carmen](https://avatars.discourse-cdn.com/v4/letter/c/a9adbd/32.png) [@Carmen](https://gromacs.bioexcel.eu/u/Carmen)\
**Post date:** [August 30, 2020, 9:18am UTC](https://gromacs.bioexcel.eu/t/external-potential-module-for-pulling-simulations/734/1 "2020-08-30T09:18:41Z")

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GROMACS version: 2020.3  
GROMACS modification: No

I am conducting pulling simulations and need to provide an external module for the potential. I have no clue how to write the external module, and I could not find a sample anywhere. Where can I find proper instructions/a sample module I can take as a reference?

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**Author:** ![hess](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/hess/32/416_2.png) [@hess](https://gromacs.bioexcel.eu/u/hess)\
**Post date:** [November 17, 2020, 8:01am UTC](https://gromacs.bioexcel.eu/t/external-potential-module-for-pulling-simulations/734/2 "2020-11-17T08:01:42Z")

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I don’t know if your post is still relevant. Why do you need to provide an external module for the potential? When using normal, harmonic pull potentials no external module is needed. Currently the external module interface only supports AWH.