# Fatal Error "Invalid dihedral type 180

**URL:** <https://gromacs.bioexcel.eu/t/fatal-error-invalid-dihedral-type-180/6744>\
**Category:** User discussions\
**Tags:** pdb2gmx, forcefield, mdp-parameters\
**Created:** [July 3, 2023, 6:57pm UTC](https://gromacs.bioexcel.eu/t/fatal-error-invalid-dihedral-type-180/6744 "2023-07-03T18:57:43Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Abhishek\_cupb](https://avatars.discourse-cdn.com/v4/letter/a/958977/32.png) [@Abhishek\_cupb](https://gromacs.bioexcel.eu/u/Abhishek_cupb)\
**Post date:** [July 3, 2023, 6:57pm UTC](https://gromacs.bioexcel.eu/t/fatal-error-invalid-dihedral-type-180/6744/1 "2023-07-03T18:57:43Z")

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GROMACS version:2023  
GROMACS modification: No  
Hope you are doing well. I have generated the topology of graphene oxide but after solvation I am getting the error " Invalid dihedral type 180 ". I am unable to locate this function type format error. I request you to please go through the commands and files I have attached below and help me resolve this issue.

Commands

Structure 17x17 GO built in Polypargen and submitted for OPLSAA topology parameters.  
gmx editconf -f go.gro -o GO.gro (convert to correct the gro file for visualisation in vmd)  
gmx editconf -f go.gro -o GO.pdb  
rtp and itp obtained from TppMKTOP  
included in oplsaaerg.ff  
ffoplsaa.itp edited and itp files included  
gmx pdb2gmx -f GO.gro -o Tpp.gro  
Topology was successfully generated  
gmx editconf -f Tpp.gro -d 1.0 -bt cubic -o box.gro  
gmx solvate -cp box.gro -o solv.gro -p topol.top  
gmx grompp -f ions.mdp -c solv.gro -p topol.top -o ions.tpr  
Errors “no default bond, angle, dihedral types”  
parameters taken from lack.itp and copied in Tpp.itp  
gmx grompp -f ions.mdp -c solv.gro -p topol.top -o ions.tpr  
Error “Invalid dihedral type 180”

 ![Screenshot from 2023-07-03 17-53-41](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/b/b113965ddd18ec4fb0e1a803c439cb2b48001729.png)

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**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [July 3, 2023, 7:10pm UTC](https://gromacs.bioexcel.eu/t/fatal-error-invalid-dihedral-type-180/6744/2 "2023-07-03T19:10:18Z")

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This topology should not generate that error since there are no dihedrals defined. In fact, there are no atoms defined, so this is basically a useless topology. It just defines water around an “Other” type that has nothing in it.

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<div class="post-metadata">

**Author:** ![Abhishek\_cupb](https://avatars.discourse-cdn.com/v4/letter/a/958977/32.png) [@Abhishek\_cupb](https://gromacs.bioexcel.eu/u/Abhishek_cupb)\
**Post date:** [July 4, 2023, 4:49am UTC](https://gromacs.bioexcel.eu/t/fatal-error-invalid-dihedral-type-180/6744/3 "2023-07-04T04:49:26Z")

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Dear Justin,  
I apologise for the incomplete upload of the topology (due to limited characters). Please check the actual topology attached below. I was unable to upload or copy paste the entire topology before.  
[topol.top](https://gromacs.bioexcel.eu/uploads/short-url/oAdyMQXK5Okavw4k9XvkqqZQYnb.top) (291.1 KB)

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<div class="post-metadata">

**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [July 8, 2023, 10:20am UTC](https://gromacs.bioexcel.eu/t/fatal-error-invalid-dihedral-type-180/6744/4 "2023-07-08T10:20:57Z")

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The error must be coming from somewhere upstream in the force field files, either through one of the macros defined or from some parameters that are referenced there.