[gmx-users] Urea topology problem

David van der Spoel spoel at xray.bmc.uu.se
Thu Dec 18 19:50:03 CET 2008


Rebeca García Fandiño wrote:
> Hello,
> I don´t understand the correction I should do from itp.
> I have removed from the urea original urea.itp these lines,

don't use this model. do a proper literature search.

>  
> #ifdef Boek
>      1       C       1    UREA      C1       1   0.38
>      2       O       1    UREA      O2       1  -0.38
>      3      NT       1    UREA      N3       2  -0.83
>      4       H       1    UREA      H4       2   0.415
>      5       H       1    UREA      H5       2   0.415
>      6      NT       1    UREA      N6       3  -0.83
>      7       H       1    UREA      H7       3   0.415
>      8       H       1    UREA      H8       3   0.415
> #else
>  #endif[ moleculetype ]
>  
> so now, my urea.itp file is:
> 
> ; name nrexcl
> Urea 3
> [ atoms ]
> ; nr type resnr residu atom cgnr charge
> 1 C 1 UREA C1 1 0.683
> 2 O 1 UREA O2 1 -0.683
> 3 NT 1 UREA N3 2 -0.622
> 4 H 1 UREA H4 2 0.346
> 5 H 1 UREA H5 2 0.276
> 6 NT 1 UREA N6 3 -0.622
> 7 H 1 UREA H7 3 0.346
> 8 H 1 UREA H8 3 0.276
> [ bonds ]
> ; ai aj funct b0 kb
> 3 4 1 1.000000e-01 3.744680e+05
> 3 5 1 1.000000e-01 3.744680e+05
> 6 7 1 1.000000e-01 3.744680e+05
> 6 8 1 1.000000e-01 3.744680e+05
> 1 2 1 1.230000e-01 5.020800e+05
> 1 3 1 1.330000e-01 3.765600e+05
> 1 6 1 1.330000e-01 3.765600e+05
> [ pairs ]
> ; ai aj funct c6 c12
> 2 4 1 0.000000e+00 0.000000e+00
> 2 5 1 0.000000e+00 0.000000e+00
> 2 7 1 0.000000e+00 0.000000e+00
> 2 8 1 0.000000e+00 0.000000e+00
> 3 7 1 0.000000e+00 0.000000e+00
> 3 8 1 0.000000e+00 0.000000e+00
> 4 6 1 0.000000e+00 0.000000e+00
> 5 6 1 0.000000e+00 0.000000e+00
> [ angles ]
> ; ai aj ak funct th0 cth
> 1 3 4 1 1.200000e+02 2.928800e+02
> 1 3 5 1 1.200000e+02 2.928800e+022 1 6 1 1.215000e+02 5.020800e+02
> 3 1 6 1 1.170000e+02 5.020800e+02
> [ dihedrals ]
> ; ai aj ak al funct phi cp mult
> 2 1 3 4 1 1.800000e+02 3.347200e+01 2.000000e+00
> 6 1 3 4 1 1.800000e+02 3.347200e+01 2.000000e+00
> 2 1 3 5 1 1.800000e+02 3.347200e+01 2.000000e+00
> 6 1 3 5 1 1.800000e+02 3.347200e+01 2.000000e+00
> 2 1 6 7 1 1.800000e+02 3.347200e+01 2.000000e+00
> 3 1 6 7 1 1.800000e+02 3.347200e+01 2.000000e+00
> 2 1 6 8 1 1.800000e+02 3.347200e+01 2.000000e+00
> 3 1 6 8 1 1.800000e+02 3.347200e+01 2.000000e+00
> [ dihedrals ]
> ; ai aj ak al funct q0 cq
> 3 4 5 1 2 0.000000e+00 1.673600e+02
> 6 7 8 1 2 0.000000e+00 1.673600e+02
> 1 3 6 2 2 0.000000e+00 1.673600e+02
> 
> 4 3 5 1 1.200000e+02 3.347200e+02
> 1 6 7 1 1.200000e+02 2.928800e+02
> 1 6 8 1 1.200000e+02 2.928800e+02
> 7 6 8 1 1.200000e+02 3.347200e+02
> 2 1 3 1 1.215000e+02 5.020800e+02
> 
>  
> Following Chapter 5 in the manual (page 102), the file described for 
> urea.itp is the same as mine. For the topology (page 103)
> #include "ffgmx.itp" is used, but I don´t see any more different.
> With this modification in the urea.itp I get the same error. Any idea of 
> what could be the problem?
> Thank you very much for your help,
>  
>  Rebeca Garcia 
> Parc Cientific de Barcelona
>  regafan at hotmail.com <mailto:regafan at hotmail.com>
> 
> 
>  
> 
> 
>  > Date: Thu, 18 Dec 2008 09:21:41 -0500
>  > From: jalemkul at vt.edu
>  > To: gmx-users at gromacs.org
>  > Subject: Re: [gmx-users] Urea topology problem
>  >
>  >
>  >
>  > Rebeca García Fandiño wrote:
>  >
>  > <snip>
>  >
>  > >
>  > > ERROR 1 [file solvated.top, line 39]:
>  > >
>  > > atom C1 (Res UREA-1) has mass 0
>  > >
>  > >
>  >
>  > In urea.itp, no masses are defined. If you correct the format of this 
> file (see
>  > Chapter 5 of the manual), then this issue should be resolved.
>  >
>  >
>  > >
>  > > Which force field does this urea.itp correspond to? Where should it 
> look
>  > > for the atomtypes of urea?
>  > >
>  > >
>  >
>  > The .atp file corresponding to the force field you are using 
> (ffG43a2). The
>  > atomtypes for urea appear to be generic for use with the Gromos96 
> force fields.
>  > There are specific atomtypes within ffG53a6 for urea, if you want to 
> use the
>  > newer force field (check the ffG53a6.rtp file for the urea parameters).
>  >
>  > -Justin
>  >
>  >
>  > >
>  > > Thank you very much for your help,
>  > >
>  > >
>  > >
>  > > Rebeca Garcia
>  > >
>  > > Parc Cientific de Barcelona
>  > >
>  > > regafan at hotmail.com
>  > >
>  > >
>  > > 
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>  > >
>  > >
>  > > 
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>  > --
>  > ========================================
>  >
>  > Justin A. Lemkul
>  > Graduate Research Assistant
>  > Department of Biochemistry
>  > Virginia Tech
>  > Blacksburg, VA
>  > jalemkul[at]vt.edu | (540) 231-9080
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-- 
David van der Spoel, Ph.D., Professor of Biology
Molec. Biophys. group, Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205. Fax: +4618511755.
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://folding.bmc.uu.se



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