[gmx-users] ionomer topolgy

Ehsan Sadeghi esa38 at sfu.ca
Fri Sep 27 21:17:50 CEST 2013


Many thanks Justin.

Here is my .pdb file:

ATOM      1  C   LIG     1     -10.450   5.214  -1.717  1.00  0.00           C  
ATOM      2  C   LIG     1      -8.424   5.477  -1.030  1.00  0.00           C  
ATOM      3  C   LIG     1      -6.603   5.864  -0.166  1.00  0.00           C  
ATOM      4  F   LIG     1      -6.651   6.230  -1.691  1.00  0.00           F  
ATOM      5  F   LIG     1      -8.417   4.546  -2.349  1.00  0.00           F  
ATOM      6  C   LIG     1      -5.705   3.003   1.204  1.00  0.00           C  
ATOM      7  F   LIG     1      -7.247   5.032   1.683  1.00  0.00           F  
ATOM      8  F   LIG     1      -8.521   5.307   0.400  1.00  0.00           F  
ATOM      9  C   LIG     1      -3.913   4.878   2.109  1.00  0.00           C  
ATOM     10  F   LIG     1      -4.358   3.650  -0.024  1.00  0.00           F  
ATOM     11  F   LIG     1      -6.198   1.346   0.214  1.00  0.00           F  
ATOM     12  C   LIG     1      -1.306   5.673   2.286  1.00  0.00           C  
ATOM     13  F   LIG     1      -3.429   3.111   0.668  1.00  0.00           F  
ATOM     14  F   LIG     1      -2.358   3.855   1.570  1.00  0.00           F  
ATOM     15  C   LIG     1       0.246   3.040   2.048  1.00  0.00           C  
ATOM     16  F   LIG     1      -0.514   4.358   3.241  1.00  0.00           F  
ATOM     17  F   LIG     1      -0.928   3.807   1.741  1.00  0.00           F  
ATOM     18  C   LIG     1       1.925   3.706   2.014  1.00  0.00           C  
ATOM     19  F   LIG     1      -0.226   2.548   0.094  1.00  0.00           F  
ATOM     20  F   LIG     1       0.215   1.482   1.590  1.00  0.00           F  
ATOM     21  F   LIG     1     -11.789   4.355  -2.598  1.00  0.00           F  
ATOM     22  F   LIG     1     -11.552   4.133  -0.632  1.00  0.00           F  
ATOM     23  F   LIG     1       2.299   2.385   2.438  1.00  0.00           F  
ATOM     24  F   LIG     1       1.831   1.994   1.526  1.00  0.00           F  
ATOM     25  OM  SCH     2       3.334   3.720   1.360  1.00  0.00           O  
ATOM     26  C   SCH     2       5.273   2.985   0.897  1.00  0.00           C  
ATOM     27  C   SCH     2       6.100   2.445   1.642  1.00  0.00           C  
ATOM     28  F   SCH     2       4.528   2.997   1.631  1.00  0.00           F  
ATOM     29  F   SCH     2       6.122   3.473   0.467  1.00  0.00           F  
ATOM     30  C   SCH     2       7.274   1.746   2.026  1.00  0.00           C  
ATOM     31  OM  SCH     2       5.454   2.160   2.446  1.00  0.00           O  
ATOM     32  F   SCH     2       6.788   2.944   0.993  1.00  0.00           F  
ATOM     33  F   SCH     2       7.031   1.025   2.779  1.00  0.00           F  
ATOM     34  F   SCH     2       8.010   2.431   2.393  1.00  0.00           F  
ATOM     35  F   SCH     2       7.678   1.241   1.173  1.00  0.00           F  
ATOM     36  C   SCH     2       5.042   1.305   2.243  1.00  0.00           C  
ATOM     37  C   SCH     2       5.168   0.043   2.583  1.00  0.00           C  
ATOM     38  F   SCH     2       4.938   1.296   1.178  1.00  0.00           F  
ATOM     39  F   SCH     2       4.377   1.446   3.070  1.00  0.00           F  
ATOM     40  S   SCH     2       5.516  -1.463   2.733  1.00  0.00           S  
ATOM     41  F   SCH     2       4.304   0.015   3.213  1.00  0.00           F  
ATOM     42  F   SCH     2       6.073   0.088   2.014  1.00  0.00           F  
ATOM     43  O   SCH     2       4.555  -2.079   3.473  1.00  0.00           O  
ATOM     44  H   SCH     2       4.772  -3.020   3.567  1.00  0.00           H  
ATOM     45  O   SCH     2       6.692  -1.508   1.977  1.00  0.00           O  
ATOM     46  O   SCH     2       6.001  -2.846   2.762  1.00  0.00           O  
CONECT    1    2   21   22                                            
CONECT    2    1    3    4    5                                       
CONECT    2                                                           
CONECT    3    2    6    7    8                                       
CONECT    3                                                           
CONECT    4    2                                                      
CONECT    5    2                                                      
CONECT    6    3    9   10   11                                       
CONECT    6                                                           
CONECT    7    3                                                      
CONECT    8    3                                                      
CONECT    9    6   12   13   14                                       
CONECT    9                                                           
CONECT   10    6                                                      
CONECT   11    6                                                      
CONECT   12    9   15   16   17                                       
CONECT   12                                                           
CONECT   13    9                                                      
CONECT   14    9                                                      
CONECT   15   12   18   19   20                                       
CONECT   15                                                           
CONECT   16   12                                                      
CONECT   17   12                                                      
CONECT   18   15   23   24   25                                       
CONECT   18                                                           
CONECT   19   15                                                      
CONECT   20   15                                                      
CONECT   21    1                                                      
CONECT   22    1                                                      
CONECT   23   18                                                      
CONECT   24   18                                                      
CONECT   25   18   26                                                 
CONECT   26   25   27   28   29                                       
CONECT   26                                                           
CONECT   27   26   30   31   32                                       
CONECT   27                                                           
CONECT   28   26                                                      
CONECT   29   26                                                      
CONECT   30   27   33   34   35                                       
CONECT   30                                                           
CONECT   31   27   36                                                 
CONECT   32   27                                                      
CONECT   33   30                                                      
CONECT   34   30                                                      
CONECT   35   30                                                      
CONECT   36   31   37   38   39                                       
CONECT   36                                                           
CONECT   37   36   40   41   42                                       
CONECT   37                                                           
CONECT   38   36                                                      
CONECT   39   36                                                      
CONECT   40   37   43   45   46                                       
CONECT   40                                                           
CONECT   41   37                                                      
CONECT   42   37                                                      
CONECT   43   40   44                                                 
CONECT   44   43                                                      
CONECT   45   40                                                      
CONECT   46   40                                                      
MASTER        0    0    0    0    0    0    0    0   46    0   46    0
END

-------------------------------------------------
I already added LIG and SCH in residuetypes.dat and defined the atoms for each residue in aminoacids.rtp in gromos. When I run pdb2gmx -f nafion.pdb
I receive this error:


Warning: Starting residue LIG1 in chain not identified as Protein/RNA/DNA.
Warning: Starting residue SCH2 in chain not identified as Protein/RNA/DNA.
Problem with chain definition, or missing terminal residues.
This chain does not appear to contain a recognized chain molecule.
If this is incorrect, you can edit residuetypes.dat to modify the behavior.
8 out of 8 lines of specbond.dat converted successfully

-------------------------------------------------------
Program pdb2gmx, VERSION 4.6.3
Source code file: /home/ehssad/Downloads/Gromacs/gromacs-4.6.3/src/kernel/resall.c, line: 642

Fatal error:
Residue 'LIG' not found in residue topology database
For more information and tips for troubleshooting, please check the GROMACS


Thank you,
Ehsan



----- Original Message -----
From: "Justin Lemkul" <jalemkul at vt.edu>
To: "Discussion list for GROMACS users" <gmx-users at gromacs.org>
Sent: Friday, September 27, 2013 11:50:13 AM
Subject: Re: [gmx-users] ionomer topolgy



On 9/27/13 2:34 PM, Ehsan Sadeghi wrote:
> Hello Gromacs users,
>
> I am the beginner in Gromacs. I want to simulate ionomer in water. I could
> not find a pdb file for my case, and I tried to draw the ionomer in Avogadro
> software and generated the pdb file. However, gmx cannot find my residue
> names. I added my residue name to residuetypes.dat and added the residue in
> aminoacids.rtp in gromos. I does not work and it cannot find my new residue.
> What should I do?
>

Well, there are several Gromos parameter sets; have you modified and then chosen 
the correct one?  In the absence of more detail, it's hard to figure out what's 
gone wrong.

> I also have some question regarding the .rtp file. Do you I need to include [
> bonds] , [angles], [dihedrals] as well? How can I find charge and charge
> groups in the [ atoms] section.
>

You need to at least specify [bonds], from which the angles and dihedrals can be 
generated.  If you have planar groups, you need to specify [impropers] for them.

Parametrization methods vary by force field, but if you're using a Gromos 
parameter set, most of the functional groups should be easily transferable to 
new species.  If you are dealing with something totally new, then you need to 
derive the charges yourself.  Details should be available in the primary 
literature for whatever parameter set you've chosen, as well as publications by 
others.  Prepare to invest some time here; it's not necessarily trivial to 
derive the new values.

-Justin

-- 
==================================================

Justin A. Lemkul, Ph.D.
Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 601
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441

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