[gmx-users] -rtpo option for pdb2gmx

Justin Lemkul jalemkul at vt.edu
Sat Mar 24 18:54:08 CET 2018

On 3/24/18 12:19 AM, Robert König wrote:
> Hello,
> I try to use a modified OPLSAA forcefield with GROMACS 2018 and I get this error:
> -------------------------------------------------------
> Program:     gmx pdb2gmx, version 2018
> Source file: src/gromacs/gmxpreprocess/resall.cpp (line 535)
> Fatal error:
> Found rtp entries for 'ACE' in both 'aminoacids' and
> './oplsaa.ff/ffoplsgas.rtp'. If you want the first definition to override the
> second one, set the -rtpo option of pdb2gmx.
> For more information and tips for troubleshooting, please check the GROMACS
> website at http://www.gromacs.org/Documentation/Errors
> -------------------------------------------------------
> What is the -rtpo option of pdb2gmx and how can I use it? I didnt find documentation or discussion for that, where can I get it?

I don't think that's an actual option, so that error message needs to be 

OPLS has "ACE" as an acetyl cap, so either pick a new name for your 
residue or generate a separate force field rather than trying to hack 
the existing one.



Justin A. Lemkul, Ph.D.
Assistant Professor
Virginia Tech Department of Biochemistry

303 Engel Hall
340 West Campus Dr.
Blacksburg, VA 24061

jalemkul at vt.edu | (540) 231-3129


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