# CGenFF ligand: No default bond/angle/dihedral types error in GROMACS

**URL:** <https://gromacs.bioexcel.eu/t/cgenff-ligand-no-default-bond-angle-dihedral-types-error-in-gromacs/13309>\
**Category:** User discussions\
**Created:** [March 17, 2026, 1:22pm UTC](https://gromacs.bioexcel.eu/t/cgenff-ligand-no-default-bond-angle-dihedral-types-error-in-gromacs/13309 "2026-03-17T13:22:54Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Kankana](https://avatars.discourse-cdn.com/v4/letter/k/7993a0/32.png) [@Kankana](https://gromacs.bioexcel.eu/u/Kankana)\
**Post date:** [March 17, 2026, 1:22pm UTC](https://gromacs.bioexcel.eu/t/cgenff-ligand-no-default-bond-angle-dihedral-types-error-in-gromacs/13309/1 "2026-03-17T13:22:54Z")

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GROMACS version: 2024.4  
GROMACS modification: Yes/No

Hi,

I am trying to include a ligand (calcein) parameterized using CGenFF with CHARMM36 (July 2022) force field in GROMACS.

However, I am getting multiple errors like:

ERROR: No default Bond types  
ERROR: No default U-B types  
ERROR: No default Proper Dih. types

What I have done:

- Generated calcein.itp from CGenFF
- Included it in topol.top
- Used **charmm36\_ljpme-jul2022.ff** for generating calcein.itp file.

My topol.top (relevant part):

[topol.top](https://gromacs.bioexcel.eu/uploads/short-url/nGapDbtBG1hcBVaqsGyB2YxYGCE.top) (899 Bytes)

[calc.txt](https://gromacs.bioexcel.eu/uploads/short-url/rLTMCGCgGWC4k6ZPpkX2dhHY9fk.txt) (29.7 KB)

Could you please suggest what I might be missing?

Your suggestions will be highly appreciated.

Thanks & Regards

Kankana Bhattacharjee

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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:** [March 17, 2026, 5:32pm UTC](https://gromacs.bioexcel.eu/t/cgenff-ligand-no-default-bond-angle-dihedral-types-error-in-gromacs/13309/2 "2026-03-17T17:32:32Z")

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Use the latest version of the C36 port for GROMACS; we updated it last month. The server is using a much newer version of the force field, which assumes that certain parameters are in the core parameter set. Those will be missing from your topology because your molecule’s topology relies on them being present in the core set, which they aren’t in the 2022 version.

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<div class="post-metadata">

**Author:** ![Kankana](https://avatars.discourse-cdn.com/v4/letter/k/7993a0/32.png) [@Kankana](https://gromacs.bioexcel.eu/u/Kankana)\
**Post date:** [March 17, 2026, 10:23pm UTC](https://gromacs.bioexcel.eu/t/cgenff-ligand-no-default-bond-angle-dihedral-types-error-in-gromacs/13309/3 "2026-03-17T22:23:58Z")

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Ok. Thank you for the clarification.

That means, have to add latest charmm36-2024.ff in GMXLIB, so that CGenFF parameters become compatible ?

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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:** [March 18, 2026, 12:47am UTC](https://gromacs.bioexcel.eu/t/cgenff-ligand-no-default-bond-angle-dihedral-types-error-in-gromacs/13309/4 "2026-03-18T00:47:32Z")

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As with any force field, either in $GMXLIB or the working directory.

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<div class="post-metadata">

**Author:** ![Kankana](https://avatars.discourse-cdn.com/v4/letter/k/7993a0/32.png) [@Kankana](https://gromacs.bioexcel.eu/u/Kankana)\
**Post date:** [March 18, 2026, 10:36am UTC](https://gromacs.bioexcel.eu/t/cgenff-ligand-no-default-bond-angle-dihedral-types-error-in-gromacs/13309/5 "2026-03-18T10:36:10Z")

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Dear Sir,

I have downloaded the latest C36 port for gromacs and included that in the topol.top file, but still getting the same error.

; Include force field files

#include “charmm36-feb2026\_ljpme\_cgenff-4.6.ff/forcefield.itp”

; Include lipid topology  
#include “DMPC.itp”

; Include ligand topology  
#include “calc.itp”

; Include water model and ions  
#include “charmm36-feb2026\_ljpme\_cgenff-4.6.ff/tip3p.itp”  
#include “charmm36-feb2026\_ljpme\_cgenff-4.6.ff/ions.itp”

[system]

DMPC-calcein-solvated system

[molecules]  
; molecule name number  
DMPC 128 ; number of lipid molecules in bilayer  
CALC 1 ; number of calcein molecules  
SOL 16298

Thanks & Regards  
Kankana Bhattacharjee