# Topology graphene

**URL:** <https://gromacs.bioexcel.eu/t/topology-graphene/10439>\
**Category:** User discussions\
**Created:** [October 29, 2024, 1:31pm UTC](https://gromacs.bioexcel.eu/t/topology-graphene/10439 "2024-10-29T13:31:32Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jacopo1](https://avatars.discourse-cdn.com/v4/letter/j/13edae/32.png) [@jacopo1](https://gromacs.bioexcel.eu/u/jacopo1)\
**Post date:** [October 29, 2024, 1:31pm UTC](https://gromacs.bioexcel.eu/t/topology-graphene/10439/1 "2024-10-29T13:31:32Z")

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GROMACS version:  
GROMACS modification: Yes/No  
Here post your question  
I have created my gro file in VMD , and now i’m looking for building topology file with the command gmx pdb2gmx -f graphene.gro -o processed.gro -p topol.top however i got this error Residue ‘GRA’ not found in residue topology database for all force field i choose how to do ?

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**Author:** ![MagnusL](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/magnusl/32/2380_2.png) [@MagnusL](https://gromacs.bioexcel.eu/u/MagnusL)\
**Post date:** [October 29, 2024, 1:39pm UTC](https://gromacs.bioexcel.eu/t/topology-graphene/10439/2 "2024-10-29T13:39:09Z")

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I’m afraid I can’t give you any details how to do it, but `pdb2gmx` is not a suitable tool. See [Fatal Error: Residue Not Found in the Residue Topology Database](https://gromacs.bioexcel.eu/t/fatal-error-residue-not-found-in-the-residue-topology-database/6215) for a starting point, but unfortunately not a complete protocol.