# Convert amber to gromacs **URL:** \ **Category:** User discussions\ **Created:** [June 2, 2026, 9:35am UTC](https://gromacs.bioexcel.eu/t/convert-amber-to-gromacs/13495 "2026-06-02T09:35:30Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Rochik](https://avatars.discourse-cdn.com/v4/letter/r/ecc23a/32.png) [@Rochik](https://gromacs.bioexcel.eu/u/Rochik)\ **Post date:** [June 2, 2026, 9:35am UTC](https://gromacs.bioexcel.eu/t/convert-amber-to-gromacs/13495/1 "2026-06-02T09:35:30Z")
Hello everyone, I had a force field for my ligand in Amber format. By using acpype i converted it to GROMACS. But the atom types in the topology file are still GAFF-like (those lowercase atom types): atoms ; nr type resi res atom cgnr charge mass ; qtot bond\_type 1 na 1 CHL N 1 -0.638039 14.01000 ; qtot -0.638 2 cc 1 CHL C 2 0.193729 12.01000 ; qtot -0.444 3 cc 1 CHL C1 3 -0.043093 12.01000 ; qtot -0.487 4 cd 1 CHL C2 4 0.053345 12.01000 ; qtot -0.434 5 c3 1 CHL C3 5 -0.304092 12.01000 ; qtot -0.738 6 hc 1 CHL H 6 0.093053 1.00800 ; qtot -0.645 Gromacs does not accept this. Do you know how to modify this topology file? Thank you