# Dihedral error in protein in gromacs version 2021

**URL:** <https://gromacs.bioexcel.eu/t/dihedral-error-in-protein-in-gromacs-version-2021/1674>\
**Category:** User discussions\
**Created:** [March 3, 2021, 12:58pm UTC](https://gromacs.bioexcel.eu/t/dihedral-error-in-protein-in-gromacs-version-2021/1674 "2021-03-03T12:58:55Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mayank](https://avatars.discourse-cdn.com/v4/letter/m/bc8723/32.png) [@mayank](https://gromacs.bioexcel.eu/u/mayank)\
**Post date:** [March 3, 2021, 12:58pm UTC](https://gromacs.bioexcel.eu/t/dihedral-error-in-protein-in-gromacs-version-2021/1674/1 "2021-03-03T12:58:55Z")

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GROMACS version: 2021  
GROMACS modification: No

While runing ion adding step I am reciving following error:

> Blockquote

> > gmx grompp -f ions.mdp -c solv.pdb -p topol.top -o ions.tpr -maxwarn 2

Ignoring obsolete mdp entry ‘title’  
Ignoring obsolete mdp entry ‘ns\_type’

NOTE 1 [file …/ions.mdp]:  
With Verlet lists the optimal nstlist is \>= 10, with GPUs \>= 20. Note  
that with the Verlet scheme, nstlist has no effect on the accuracy of  
your simulation.

Setting the LD random seed to -1763188889

Generated 168 of the 1653 non-bonded parameter combinations

ERROR 1 [file topol.top, line 26053]:  
No default Proper Dih. types

ERROR 2 [file topol.top, line 26284]:  
No default Proper Dih. types

ERROR 3 [file topol.top, line 26285]:  
No default Proper Dih. types

> Blockquote

Thank you in advance

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**Author:** ![fmahmoudinobar](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@fmahmoudinobar](https://gromacs.bioexcel.eu/u/fmahmoudinobar)\
**Post date:** [March 8, 2021, 1:53pm UTC](https://gromacs.bioexcel.eu/t/dihedral-error-in-protein-in-gromacs-version-2021/1674/2 "2021-03-08T13:53:48Z")

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People can help you more if you provide more information about your system. For example, what proteins or molecules do you have in your topology file? Did you create the topology file yourself for a molecule? Even posting parts of your .top file that produces the errors can be helpful for debugging.

Without more info, the error says: dihedral angles in your system are not defined right or are missing.

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**Author:** ![mayank](https://avatars.discourse-cdn.com/v4/letter/m/bc8723/32.png) [@mayank](https://gromacs.bioexcel.eu/u/mayank)\
**Post date:** [March 11, 2021, 11:13am UTC](https://gromacs.bioexcel.eu/t/dihedral-error-in-protein-in-gromacs-version-2021/1674/3 "2021-03-11T11:13:14Z")

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I didnt prepared a topology file by myself, I used a crystal structure monomer protien with 4 copper atoms.