# Topology file by ATB or PRODRG

**URL:** <https://gromacs.bioexcel.eu/t/topology-file-by-atb-or-prodrg/2140>\
**Category:** User discussions\
**Tags:** forcefield\
**Created:** [May 11, 2021, 6:07am UTC](https://gromacs.bioexcel.eu/t/topology-file-by-atb-or-prodrg/2140 "2021-05-11T06:07:25Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Azam](https://avatars.discourse-cdn.com/v4/letter/a/ea666f/32.png) [@Azam](https://gromacs.bioexcel.eu/u/Azam)\
**Post date:** [May 11, 2021, 6:07am UTC](https://gromacs.bioexcel.eu/t/topology-file-by-atb-or-prodrg/2140/1 "2021-05-11T06:07:25Z")

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GROMACS version:2020  
GROMACS modification: NO  
Hi  
I want to simulate a box of metaloprotein and mixture of water and a ionic liquid in gromacs.  
For parametrize ionic liquid , i used ATB server. When i submitted the pdb file, in ATB server, countered this erroe:

Your structure file could not be processed. Error was: Mol\_Data Error: Missing connectivities for atoms [38]

how i can solve this problem?