[gmx-users] Re: Parameters for AOT molecule/Too few parameters on line
Lum Nforbi
lumngwegia at gmail.com
Fri Apr 2 06:07:34 CEST 2010
Justin,
I appreciate your reply. Actually, I have read through the section of
building parameter files in chap. 5 several times. The only reason for using
atom types instead of numbers is because that is the way they are
represented in the ffcharmmbon.itp and ffcharmmnb.itp files. Numbers are not
used in these force fields. The [ bondtypes ] below is a portion of the
[bondtypes ] listed in the ffcharmmbon.itp file. I will definitely use
numbers.
[ bondtypes ]
; i j func b0 kb
CST OST 1 0.116 784884.928
SS FE 1 0.232 209200.0
C C 1 0.1335 502080.0
CA CA 1 0.1375 255224.0
CE1 CE1 1 0.134 368192.0
CE1 CE2 1 0.1342 418400.0
CE1 CT2 1 0.1502 305432.0
Thank you,
Lum
> Lum Nforbi wrote:
> > Hello all,
> >
> > I have built a parameter file for the AOT surfactant molecule and
> > tried to minimize the energy of a mixture of several of this molecule
> > and water molecules but I have the warnings at the bottom part of this
> > mail. Gromacs basically goes through all the lines of parameters
> > starting from [ bonds ] and says the parameters are too few. I am also
> > using the charmm force field.
> >
> > Here is the way I constructed the aot.itp parameter file. I am not
> > sure this is correct. Excerpts of the parameter file are belowl.
> >
> > - I drew the AOT molecule and did the bond and angle connections in the
> > molecule.The atom names are provided by the ffcharmm27.atp file. All
>
> The .atp file contains atom types, not atom names. Your [bonds], [angles],
> etc.
> should be numbers, not atom types or names. For instance, if atoms 1 and
> 2
> are bonded:
>
> [ bonds ]
> 1 2 (function type, etc)
> values are obtained from the ffcharmmbon.itp file and ffcharmmnb.itp file.
> > - I am not sure how to build the dihedrals since the are X's in the [
> > dihedrals ] section of the ffcharmmbon.itp file.
> >
>
> As Mark indicated earlier, an X is simply a wildcard - it can correspond to
> any
> number of atom types.
>
> > My question is: Why does the program say I have few parameters while I
> > just out together parameters from the charmm27 force field? Please, if I
> > am doing something wrong, can someone let me know?
> > [ bonds ]
> > ; i j func b0 kb
> > SL O2L 1 0.1448 451872.0
>
> You're using either atom types or names in these sections, which is
> completely
> incorrect. Please have a thorough read through Chapter 5 of the manual.
>
> <snip>
>
> > NOTE 1 [file aotwater.top, line 19]:
> > System has non-zero total charge: -1.350000e+01
> >
>
> I would also be *very* concerned about this line. You have a negative
> charge of
> -13.5, indicating that whatever charges you've assigned to your small
> molecule
> have left a fractional charge on the system, which is clearly non-physical.
>
> -Justin
>
> > processing coordinates...
> > double-checking input for internal consistency...
> > renumbering atomtypes...
> > converting bonded parameters...
> > initialising group options...
> > processing index file...
> > Analysing residue names:
> > Opening library file /usr/local/gromacs/share/gromacs/top/aminoacids.dat
> > There are: 60 OTHER residues
> > There are: 0 PROTEIN residues
> > There are: 0 DNA residues
> > Analysing Other...
> > Making dummy/rest group for T-Coupling containing 1110 elements
> > Making dummy/rest group for Acceleration containing 1110 elements
> > Making dummy/rest group for Freeze containing 1110 elements
> > Making dummy/rest group for Energy Mon. containing 1110 elements
> > Making dummy/rest group for VCM containing 1110 elements
> > Number of degrees of freedom in T-Coupling group rest is 3192.00
> > Making dummy/rest group for User1 containing 1110 elements
> > Making dummy/rest group for User2 containing 1110 elements
> > Making dummy/rest group for XTC containing 1110 elements
> > Making dummy/rest group for Or. Res. Fit containing 1110 elements
> > Making dummy/rest group for QMMM containing 1110 elements
> > T-Coupling has 1 element(s): rest
> > Energy Mon. has 1 element(s): rest
> > Acceleration has 1 element(s): rest
> > Freeze has 1 element(s): rest
> > User1 has 1 element(s): rest
> > User2 has 1 element(s): rest
> > VCM has 1 element(s): rest
> > XTC has 1 element(s): rest
> > Or. Res. Fit has 1 element(s): rest
> > QMMM has 1 element(s): rest
> > Checking consistency between energy and charge groups...
> >
> > NOTE 2 [file aotwater_min.mdp, line unknown]:
> > You are using a plain Coulomb cut-off, which might produce artifacts.
> > You might want to consider using PME electrostatics.
> >
> >
> > This run will generate roughly 1 Mb of data
> > writing run input file...
> >
> > There were 2 notes
> >
> > There were 142 warnings
> >
> > -------------------------------------------------------
> > Program grompp, VERSION 4.0.5
> > Source code file: gmx_fatal.c, line: 481
> >
> > Fatal error:
> > Too many warnings (142), grompp terminated.
> > If you are sure all warnings are harmless, use the -maxwarn option.
> > -------------------------------------------------------
> >
> >
> > I appreciate your answers.
> >
> > Lum
> >
>
> --
> ========================================
>
> Justin A. Lemkul
> Ph.D. Candidate
> ICTAS Doctoral Scholar
> MILES-IGERT Trainee
> Department of Biochemistry
> Virginia Tech
> Blacksburg, VA
> jalemkul[at]vt.edu | (540) 231-9080
> http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>
> ========================================
>
>
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> End of gmx-users Digest, Vol 72, Issue 8
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