# Problems with protein receptors in generating TOP files

**URL:** https://gromacs.bioexcel.eu/t/problems-with-protein-receptors-in-generating-top-files/5167
**Category:** User discussions
**Tags:** mdrun
**Created:** [November 4, 2022, 2:12am UTC](https://gromacs.bioexcel.eu/t/problems-with-protein-receptors-in-generating-top-files/5167 "2022-11-04T02:12:47Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Songlu](https://avatars.discourse-cdn.com/v4/letter/s/b19c9b/32.png) [@Songlu](https://gromacs.bioexcel.eu/u/Songlu)
#### Post date: [November 4, 2022, 2:12am UTC](https://gromacs.bioexcel.eu/t/problems-with-protein-receptors-in-generating-top-files/5167/1 "2022-11-04T02:12:47Z")

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GROMACS version:  
GROMACS modification: Yes/No  
Here post your question Fatal error:  
Atom OCT1 in residue GLN 509 was not found in rtp entry CGLN with 18 atoms  
while sorting atoms.  
What should I do when preparing the TOP file?