On 23/05/2012 6:42 PM, Alan wrote:
Thanks Justin, you were right. In the end gmxdump helped to clear some doubts but I wished it would be less painfully.

One useful approach is to simplify the system as much as possible before producing the .tpr and using gmxdump. The necessary cross-referencing is easier to see when the complexity of the contents is low.

Mark


Cheers,

Alan

On 22 May 2012 12:36, Justin A. Lemkul <jalem...@vt.edu <mailto:jalem...@vt.edu>> wrote:



    On 5/22/12 12:46 PM, Alan wrote:

        Hi Justin, your suggestion got close. However, let me give an
        example. You can
        use the Gly-Gly-Gly example I am attaching and do this:

        pdb2gmx -ff amber99sb -f aGGG.pdb -o aGGG_.pdb -p aGGG.top
         -water none
        /sw/bin/grompp -c aGGG_.pdb -p aGGG.top -f SPE.mdp -o aGGG.tpr
        -pp aGGGp.top

        if you look at aGGGp.top I can't find which parameters were
        used for

        [ dihedrals ]
; ai aj ak al funct c0 c1 c2
           c3            c4            c5
            2     1     5     6     9

        I.e., for proper dihedral (H1-     N-    CA-   HA1), I can't find
        in amber99sb.ff/forcefield.itp any combination that handles
        parameters for
        X-N-CA-X or X-CA-N-X, so how grompp is interpreting this dihedral?


    Make sure you're looking at types, not names.  The type sequence
    here is H-N3-CT-HP, which I think is mapped to this dihedral:

     X   CT  N3  X     9       0.0      0.65084     3  ; JCC,7,(1986),230

    Running gmxdump on the .tpr file will show it for sure; I had
    assumed it would be in the post-processed topology as well, but I
    guess not.

    -Justin

        Thanks,

        Alan

        On 21 May 2012 18:50, Justin A. Lemkul <jalem...@vt.edu
        <mailto:jalem...@vt.edu>
        <mailto:jalem...@vt.edu <mailto:jalem...@vt.edu>>> wrote:



           On 5/21/12 2:43 PM, Alan wrote:

               Hi there,

               Is there an option in pdb2gmx that when generating the
        top/itp file, it
               could
               show the parameters explicitly? e.g.:

               Instead of:
               [ dihedrals ]
; ai aj ak al funct c0 c1 c2
                   c3
                    5    13    11    12     4
                   11    15    13    14     4
                   15    23    21    22     4
                   21    25    23    24     4
                   25    32    31    33     4

               (my hard hand modifications)

               [ dihedrals ] ; impropers
               ; treated as propers in GROMACS to use correct AMBER
        analytical function
               ;    i      j      k      l   func   phase     kd      pn
                     5     13     11     12      4   180.00  43.93200
          2 ;     CA-     N-
               C-     O
                    11     15     13     14      4   180.00   4.60240
          2 ;      C-    CA-
               N-     H
                    15     23     21     22      4   180.00  43.93200
          2 ;     CA-     N-
               C-     O
                    21     25     23     24      4   180.00   4.60240
          2 ;      C-    CA-
               N-     H
                    25     32     31     33      4   180.00  43.93200
          2 ;     CA-   OC1-
               C-   OC2

               I mean, if the parameters that are hiding in e.g.
               ...gromacs/top/amber99sb.ff
               could be showed in the top/itp file for human readers,
        that would be great.


           You can obtain these parameters (I believe) by running
        grompp with the -pp
           option.  If you think it would be a useful feature for
        pdb2gmx, file a
           feature request on redmine.gromacs.org
        <http://redmine.gromacs.org> <http://redmine.gromacs.org>.

           -Justin

           --
           ==============================__==========


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

           ==============================__==========
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        --
        Alan Wilter SOUSA da SILVA, DSc
        Bioinformatician, UniProt - PANDA, EMBL-EBI
        CB10 1SD, Hinxton, Cambridge, UK
        +44 1223 49 4588 <tel:%2B44%201223%2049%204588>


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

    Justin A. Lemkul, Ph.D.
    Research Scientist
    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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CB10 1SD, Hinxton, Cambridge, UK
+44 1223 49 4588




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