[gmx-users] Problem in .gro file

[Justin Lemkul]

On 6/29/15 8:00 AM, faride badalkhani wrote:
> Dear all,
>
> I am trying to simulate a hyperbranced polymer (a dendrimer) with gromacs.
> Therefore, I have parametrized the GROMOS 53A6 FF, and executed pdb2gmx,
> and got a command as follows:
> "You have successfully generated a topology from : G3-Neutral.pdb
> The Pamam force field and the spce water model are used."
>
> But, when I open the G3-Neutral_processed.gro with VMD, it is in a strange
> shape, and hasnt got the correct form af a dendrimer. It seems that it
> annot realize the correct connections between residues in a branched
> polymar such as dendrimer.
>

The bonds you see in a visualization software are guessed based on distances and 
have nothing to do with the topology, which is definitive.

Probably your input PDB file is misformatted such that the coordinates are 
misinterpreted by pdb2gmx.  The file format is fixed, so any shifting of columns 
causes junk to be produced.

-Justin

-- 
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Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

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