kartik mehra wrote:

Dear Justin,

1. They are the same protein ( 2 copies of the same protein)


OK, that makes life a little easier :-)

2. The order in the .gro file seems fine... Basically it lists the co-ordinates of a single copy of peptide and then the solvent molecule ... I presume since the .top file has 4 copies of the same molecule, this is how the .gro file should look ?

That's the problem. Everything that's in the .top file must be in the .gro file. Therefore, if you have 4 copies of your protein, you *must* provide the coordinates for four copies of the protein in the .gro file. Otherwise, how does mdrun know where they are to do any calculations?

3. Also is there an easier way of dealing with the modification of number of solvent molecules ( since the co-ordinates involve a factor of 3 arising out of the description of SPC atoms ... )


When you run genbox, use the -p flag, giving the name of your topology file. It will modify the [ molecules ] section to add the number of water molecules it placed in your system. Otherwise, genbox prints out how many water molecules it added, and you can type them in yourself. Not terribly laborious, either way, really.

-Justin





Thanks




    -
    From: *Justin A. Lemkul* <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
    Date: Mon, Jul 7, 2008 at 11:30 AM
    Subject: Re: [gmx-users] simulating two peptides in a box
    To: Discussion list for GROMACS users <[email protected]
    <mailto:[email protected]>>




    kartik mehra wrote:


           Dear Gromacs USers


        1. Please disregard the previous mail which was sent from a
        different email id ....

        2. I have copied the relevant portion here ...( previous mail
        had a wrong command ...I have copied the actual command here)

        Dear Justin,

         Here is the exact error message : ( Here I have tried to
        simulate 4 protein molecules in a box ...basically I am
        looking at multiple molecule interactions )

        *grompp  -f em.mdp -c nt17_sol.gro -o nt17_em.tpr -p nt17.top*

        *checking input for internal consistency...
        calling /usr/bin/cpp...
        processing topology...
        Generated 279 of the 1225 non-bonded parameter combinations
        Excluding 3 bonded neighbours for Protein 4
        Excluding 2 bonded neighbours for SOL 8813
        NOTE:
         System has non-zero total charge: 4.000000e+00

        processing coordinates...
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (N - OW)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (H1 - HW1)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (H2 - HW2)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (H3 - OW)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (CA - HW1)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (CB - HW2)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (CG - OW)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (SD - HW1)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (CE - HW2)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (C - OW)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (O - HW1)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (N - HW2)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (H - OW)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (CA - HW1)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (CB - HW2)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (C - OW)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (O - HW1)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (N - HW2)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (H - OW)
        Warning: atom names in nt17.top and nt17_sol.gro don't match
        (CA - HW1)
        (more than 20 non-matching atom names)
        WARNING 1 [file "nt17.top", line 1126]:
         534 non-matching atom names
         atom names from nt17.top will be used
         atom names from nt17_sol.gro will be ignored

        double-checking input for internal consistency...
        renumbering atomtypes...
        converting bonded parameters...
        #      BONDS:   17626
        #   G96BONDS:   716
        #     ANGLES:   8813
        #  G96ANGLES:   1040
        #      PDIHS:   372
        #      IDIHS:   320
        #       LJ14:   1104
        initialising group options...
        processing index file...
        Analysing residue names:
        Opening library file
        /usr/local/gromacs/3.3.1/64/gnu/ib/share/gromacs/top/aminoacids.dat
        There are:  8813      OTHER residues
        There are:    68    PROTEIN residues
        There are:     0        DNA residues
        Analysing Protein...
        Analysing Other...
        Making dummy/rest group for T-Coupling containing 27151 elements
        Making dummy/rest group for Acceleration containing 27151 elements
        Making dummy/rest group for Freeze containing 27151 elements
        Making dummy/rest group for Energy Mon. containing 27151 elements
        Making dummy/rest group for VCM containing 27151 elements
        Number of degrees of freedom in T-Coupling group rest is 81450.00
        Making dummy/rest group for User1 containing 27151 elements
        Making dummy/rest group for User2 containing 27151 elements
        Making dummy/rest group for XTC containing 27151 elements
        Making dummy/rest group for Or. Res. Fit containing 27151 elements
        Making dummy/rest group for QMMM containing 27151 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...
        Calculating fourier grid dimensions for X Y Z
        Using a fourier grid of 60x60x60, spacing 0.118 0.118 0.118
        writing run input file...

        Back Off! I just backed up nt17_em.tpr to ./#nt17_em.tpr.4#
        There was 1 warning*

        Any suggestions would be appreciated .. Also I do believe that
        the order might be a problem..but isnt an inclusion of the no
        .of molecules meant to take care of that ?

        Thanks

    OK, that's clear now.  What's happening is that grompp is finding
    water molecules where it should be finding protein.  Including a
    "number of protein molecules" does not automatically fix anything,
    necessarily.  Again, I ask, are your proteins the same?

    If they are different, you will need to have a mechanism something
    like:

    #include "Protein_A.itp"
    #include "Protein_B.itp"

    #include "spc.itp"

    #include "ions.itp"

    to get the desired behavior.

    Bottom line - check the order of the molecules in your .gro file,
    you'll likely find that the order is not the same as the topology
    expects it.

    -Justin



           ---------- Forwarded message ----------
           From: *Justin A. Lemkul* <[EMAIL PROTECTED]
        <mailto:[EMAIL PROTECTED]> <mailto:[EMAIL PROTECTED]
        <mailto:[EMAIL PROTECTED]>>>
           Date: Mon, Jul 7, 2008 at 10:50 AM
           Subject: Re: [gmx-users] simulating two peptides in a box
           To: Discussion list for GROMACS users
        <[email protected] <mailto:[email protected]>
           <mailto:[email protected] <mailto:[email protected]>>>


           Several questions come to mind, aside from trying to sift
        through
           your interpretation of error messages.  Hint: always show your
           exact command, followed by the relevant portion of the screen
           output; that way we don't have to guess what you've been up
        to :-)

           1. Do you have two different proteins, or are they the
        same?  If
           they are different, changing the number of Protein molecules in
           your topology will not be correct.  If they are the same,
        this is
           fine.

           2. Does the order of your topology follow the order of the
           coordinate file?  When you get warnings about non-matching atom
           names, you should be alert that something has gone wrong.

           -Justin

           kartik mehra wrote:

               Dear GMX Users,

               I am trying to set up a simulation box with two proteins. I
               have perused the archives about the methodology of
        doing so. I
               tried the recommended option of changing the number of
        protein
               molecules in the topology file to 2. However when I run
        grompp
               after editconf and genbox, I get warning that the
        number of co
               -ordinates do not match (since I had not updated the
        number of
               solvent molecules ...) After updating the number of solvent
               molecules, when I try running grompp again, it shows a
        warning
               that the 23644 atom names do not match in top and gro files
               and that atom names from top files are being chosen .

               Upon subsequent mdrun, the system explodes after a 1-4
               interaction warning.

               I was wondering whether anyone could help me out on
        this ... I
               do understand that the topic has been discussed pretty
        often
               but would appreciate any help ...


               Cheers

               Kartik

               PS: I have not yet tried the other suggestion of
        translation
               and rotation followed by concatenating the two files


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

           Justin A. Lemkul
           Graduate Research Assistant
           Department of Biochemistry
           Virginia Tech
           Blacksburg, VA
           jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu> | (540)
        231-9080

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

    Justin A. Lemkul
    Graduate Research Assistant
    Department of Biochemistry
    Virginia Tech
    Blacksburg, VA
    jalemkul[at]vt.edu <http://vt.edu> | (540) 231-9080
    http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

    ========================================

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

Justin A. Lemkul
Graduate Research Assistant
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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