# Segmentation fault on mdrun for two identical proteins

**URL:** https://gromacs.bioexcel.eu/t/segmentation-fault-on-mdrun-for-two-identical-proteins/9690
**Category:** User discussions
**Tags:** mdrun
**Created:** [July 19, 2024, 7:32pm UTC](https://gromacs.bioexcel.eu/t/segmentation-fault-on-mdrun-for-two-identical-proteins/9690 "2024-07-19T19:32:31Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![sben](https://avatars.discourse-cdn.com/v4/letter/s/839c29/32.png) [@sben](https://gromacs.bioexcel.eu/u/sben)
#### Post date: [July 19, 2024, 7:32pm UTC](https://gromacs.bioexcel.eu/t/segmentation-fault-on-mdrun-for-two-identical-proteins/9690/1 "2024-07-19T19:32:31Z")

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GROMACS version: 2023.1  
GROMACS modification: No

Hi! I am trying to simulate two identical proteins in a box in GROMACS, but, upon attempting to perform the mdrun for energy minimization, I am met with a segmentation fault.

I am unsure if I made the system correctly, especially with respect to the topol.top or .gro files. Any help or guidance would be super appreciated!

[topol.top](https://gromacs.bioexcel.eu/uploads/short-url/lINRl2lk07iDAqvYH9cid7eQHeB.top) (126.2 KB)

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### Author: ![Seyilaxa](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/seyilaxa/32/3136_2.png) [@Seyilaxa](https://gromacs.bioexcel.eu/u/Seyilaxa)
#### Post date: [July 20, 2024, 4:12pm UTC](https://gromacs.bioexcel.eu/t/segmentation-fault-on-mdrun-for-two-identical-proteins/9690/2 "2024-07-20T16:12:45Z")

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The topol file seems normal.  
Usually the incorrect equibrium step will lead to this error. Have you checked the trajectory or the energy change in the energy minization step?