# Does GROMOS96 53a6 support N-methyl acetamide?
**URL:** https://gromacs.bioexcel.eu/t/does-gromos96-53a6-support-n-methyl-acetamide/2950
**Category:** User discussions
**Tags:** pdb2gmx, forcefield, simulation-setup
**Created:** [October 12, 2021, 2:40pm UTC](https://gromacs.bioexcel.eu/t/does-gromos96-53a6-support-n-methyl-acetamide/2950 "2021-10-12T14:40:23Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@dkonstan](https://gromacs.bioexcel.eu/u/dkonstan)
#### Post date: [October 12, 2021, 2:40pm UTC](https://gromacs.bioexcel.eu/t/does-gromos96-53a6-support-n-methyl-acetamide/2950/1 "2021-10-12T14:40:23Z")
GROMACS version: 2016.5-foss-2018b
GROMACS modification: No
A while ago I posted a question about whether it is possible to use N-methyl acetamide with the GROMOS96 53a6 force field and no one answered and my question was greyed out for some reason. I just want to know if there is any way GROMOS96 can support a NME (N-methyl cap) residue for N-methyl acetamide, considering it is not in the force field specification (unlike ACE) but people in the literature have used GROMOS96 53a6 for NMA successfully so I don’t know…
Thank you!
Dan
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### Author:  [@TomPiggot](https://gromacs.bioexcel.eu/u/TomPiggot)
#### Post date: [October 13, 2021, 6:21pm UTC](https://gromacs.bioexcel.eu/t/does-gromos96-53a6-support-n-methyl-acetamide/2950/2 "2021-10-13T18:21:31Z")
This is an rtp entry for NME with GROMOS 54A7 I made ages ago (so worth checking it is correct yourself):
[NME]
[atoms]
N N -0.31000 0
H H 0.31000 0
CA CH3 0.00000 1
[bonds]
N H gb\_2
N CA gb\_21
[angles]
; ai aj ak gromos type
-C N H ga\_32
-C N CA ga\_31
H N CA ga\_18
[impropers]
; ai aj ak al gromos type
N -C CA H gi\_1
[dihedrals]
; ai aj ak al gromos type
-CA -C N CA gd\_14
Unless there is a good reason, I would not recommend using GROMOS 53A6 for protein/peptide simulations but a more recent GROMOS force field version.
Cheers
Tom