Errors in transmembrane protein simulation

User discussions
#1

GROMACS version:2020
GROMACS modification: Yes
Here post your question
Hello all,
I am simulating a transmembrane protein with a docked ligand. The input files for protein, membrane, and water molecules were taken from charmm membrane builder, I also used ATB for the ligand itp file.
I run energy minimization and it ended normally, then for the NVT equilibration I got errors like:

ERROR 9526 [file PROA.itp, line 190603]:
No default Position Rest. types

ERROR 9527 [file CHL1.itp, line 845]:
Incorrect number of parameters - found 2, expected 3 or 6 for Position
Rest. (after the function type).

I appreciate any help to fix this problem,
Thank you in advance,
Havva Mehralitabar

#2

Here’s your problem. You’re trying to mix two different force fields. Don’t. Build everything in CHARMM or build everything in GROMOS, not a combination of the two. The CHARMM-GUI server can call CGenFF to parametrize ligands.

#3

Thank you so much for the help