[gmx-users] gromacs.org_gmx-users Digest, Vol 123, Issue 124: reply to message 1

Guilherme Duarte Ramos Matos gduarter at uci.edu
Thu Jul 24 22:09:24 CEST 2014


Thanks for the reply!

I actually managed to solve this issue. I was building the super cell
with Mercury, the Cambridge Crystallographic Database software, but I
was not aware of connectivity issues that appeared when I built the
crystal with fragments of molecules. It was solved easily with a
different option in the packing/ slicing utility.

Thanks!

~ Guilherme

*****************************************************
Guilherme D. R. Matos
Graduate Student at UC Irvine
Mobley Group

*****************************************************


On Wed, Jul 23, 2014 at 2:48 AM,
<gromacs.org_gmx-users-request at maillist.sys.kth.se> wrote:
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> Today's Topics:
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>    1. Re: Molecular Solid PBC problem (Justin Lemkul)
>    2. about cos-accelation (Hyunjin Kim)
>    3. g_energy questions (Andy Chao)
>    4. Re: Error in system_inflate.gro coordinates does not      match
>       (RINU KHATTRI)
>    5. Angle group (Cyrus Djahedi)
>    6. Re: about cos-accelation (Dr. Vitaly Chaban)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 22 Jul 2014 20:15:23 -0400
> From: Justin Lemkul <jalemkul at vt.edu>
> To: gmx-users at gromacs.org
> Subject: Re: [gmx-users] Molecular Solid PBC problem
> Message-ID: <53CEFE9B.4010801 at vt.edu>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>
>
> On 7/22/14, 7:53 PM, Guilherme Duarte Ramos Matos wrote:
> > Dear GROMACS user community,
> >
> > I'm working with molecular dynamics of molecular solids and I am having
> > trouble to set up the calculations.
> >
> > I got the crystal structure's pdb file from the Cambridge Database and used
> > editconf to generate the coordinate file. The topology file is really
> > simple: it just carries the hamiltonian of an Einstein crystal, that is,
> > harmonic potentials binding each atom of the molecule to its lattice
> > position. The relevant part of the mdp file is:
> >
> > ; NEIGHBORSEARCHING PARAMETERS
> > ; nblist update frequency
> > nstlist                  = 1
> > ; ns algorithm (simple or grid)
> > ns_type                  = grid
> > ; Periodic boundary conditions: xyz (default), no (vacuum)
> > ; or full (infinite systems only)
> > pbc                      = xyz
> > ; nblist cut-off
> > rlist                    = 1.0
> >
> > Unfortunately, after running grompp, I get the following warning:
> >
> >   WARNING 1 [file molecule_ideal.top, line 351]:
> >    10116 non-matching atom names
> >    atom names from molecule_ideal.top will be used
> >    atom names from input.gro will be ignored
> >
> > The funny and worrying part of this problem is that all the atom types were
> > changed in the output of mdrun. The simulation just didn't crash because of
>
> As it should; gromp warned you that a huge number of atoms were out of order
> with respect to the topology, so the topology is used, and the identity and/or
> types of the atoms are changed accordingly.
>
> > the hamiltonian used. I investigated a little bit and it seemed that
> > GROMACS was not able to connect the fragments in the wall to their
> > neighboring periodic copies. That happened because fragments were numbered
> > as distinct molecules. Check this small portion of the coordinate file:
> >
>
> How did you generate the original topology?  The mismatch between coordinates
> and topology could also be causing issues with bonded geometry, because
> everything is likely to get scrambled.
>
> >     35RES     C1  211   0.017   5.561   4.241
> >     35RES     N1  212   0.033   5.362   4.363
> >     35RES     O1  213   0.145   5.367   4.163
> >     35RES     C2  214   0.074   5.421   4.245
> >     35RES     H1  215   0.057   5.283   4.386
> >     35RES     H3  216   0.087   5.628   4.238
> >     36RES     C1  217   0.017   5.561   5.526
> >     36RES     N1  218   0.033   5.362   5.648
> >     36RES     O1  219   0.145   5.367   5.448
> >     36RES     C2  220   0.074   5.421   5.530
> >     36RES     H1  221   0.057   5.283   5.671
> >     36RES     H3  222   0.087   5.628   5.523
> >     37RES     C1  223   0.017   5.561   6.811
> >     37RES     N1  224   0.033   5.362   6.933
> >     37RES     O1  225   0.145   5.367   6.733
> >     37RES     C2  226   0.074   5.421   6.815
> >     37RES     H1  227   0.057   5.283   6.956
> >     37RES     H3  228   0.087   5.628   6.808
> >     38RES     C1  229   0.753   0.786   1.671
> >     38RES     N1  230   0.770   0.587   1.793
> >     38RES     O1  231   0.882   0.592   1.593
> >     38RES     C2  232   0.811   0.646   1.675
> >     38RES     O2  233   0.636   0.631   1.973
> >     38RES     C3  234   0.687   0.665   1.868
> >     38RES     C4  235   0.672   0.798   1.799
> >     38RES     H1  236   0.794   0.508   1.816
> >     38RES     H2  237   0.696   0.797   1.593
> >     38RES     H3  238   0.824   0.852   1.668
> >     38RES     H4  239   0.707   0.870   1.855
> >     38RES     H5  240   0.579   0.817   1.779
> >
> > The molecule number 38 has 12 atoms and is inside the walls while 35, 36
> > and 37 have 6 atoms each, represent similar fragments, along the wall but
> > are accounted as isolated molecules.
> >
> > Does anyone have a suggestion to help me with this problem?
>
> If you can provide the exact details of what these molecules are and how you
> generated the topology, probably, but without that information it's a bit hard
> to suggest anything.
>
> -Justin
>
> --
> ==================================================
>
> Justin A. Lemkul, Ph.D.
> Ruth L. Kirschstein NRSA 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
> http://mackerell.umaryland.edu/~jalemkul
>
> ==================================================
>
>
>


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