[gmx-users] making topology file for infinite crystal

Vishal Agarwal vishal.iitian at gmail.com
Sun Feb 7 22:13:28 CET 2010


Dear Justin,

Thanks for replying. I really appreciate this.

Thanks,
Vishal

On Sun, Feb 7, 2010 at 3:58 PM, Justin A. Lemkul <jalemkul at vt.edu> wrote:

>
>
> Vishal Agarwal wrote:
>
>> Dear Justin,
>>
>> Thanks for replying. I guess it should be -O4 from the convention but have
>> to look more deeply to figure out that.
>> I am noticing a few more things in the ffG45a3.rtp, entries like +N in the
>> bonds and angles section. Since there is no atom type N in the monomer, are
>> these entries correct or another typo ?
>>
>>
> Probably another typo, unless glucose suddenly contains nitrogen and no one
> notified the scientific community :)  I would again suggest modifying the
> .rtp entry (in a local copy of the .rtp file), modeled after ffG53a6.rtp,
> since it appears to be more reliable.  There is no need to alter the [atoms]
> section, but it appears some of the bonded directives need some work.
>
> -Justin
>
>  Vishal
>>
>>
>>
>> On Sun, Feb 7, 2010 at 1:18 PM, Justin A. Lemkul <jalemkul at vt.edu<mailto:
>> jalemkul at vt.edu>> wrote:
>>
>>
>>
>>    Vishal Agarwal wrote:
>>
>>        Dear Justin,
>>
>>        Thanks for replying.
>>
>>               pdb2gmx -f cellulose.gro
>>
>>
>>           So then your "cellulose.gro" contains all the atoms of GLCA
>>           monomers, named exactly as the force field expects them?
>>         Have you
>>           checked against the .rtp entry?  What force field are you using?
>>
>>           ;;
>>
>>        Should they be exactly in the same order as the rtp entry ? The
>>        atom type I specified is definitely according to the standard
>>        convention of rtp entry. I am using G45a3 as the force field.
>>
>>
>>    Not to my knowledge.  As long as all of the expected atoms are
>>    there, you shouldn't have a problem.
>>
>>
>>
>>               I am getting the following error while using pdbgmx.
>>
>>               "Fatal Error:
>>               Atom -O not found in residue 2 while adding improper"
>>
>>               Atom type "O" is actually not part of the GLCA residue. Only
>>               atom type OA is part of GLCA residue.
>>
>>
>>           pdb2gmx is complaining about an atom, not an atom type.
>>         Somewhere
>>           in the .rtp file (probably within the [impropers] section, there
>>           should be a line specifying an atom named O that belongs to the
>>           preceding residue (hence the minus sign). None of my .rtp
>>        files are
>>           like this.  Did you create a custom .rtp entry?
>>
>>        ;;
>>        No I didnt create a custom rtp entry.
>>
>>               Do I need to modify the rtp entry to suit my system or
>>        does this
>>               error corresponds to something else ?
>>
>>
>>           That will depend upon the answers to the above questions.  If
>> you
>>           created the .rtp entry, then you'll have to fix the problem of
>>           naming mismatch.  If you're using the standard .rtp entry for
>> the
>>           force field, then it's easier to modify your coordinate file to
>>           match the naming expected by the force field.
>>
>>        ;;
>>        The problem I am having is where to modify my coordinate file.
>>        The residue doesnot contain a atom type 'O'.
>>
>>        Another curious question I have is suppose if I have another
>>        system where the a monomer uint say GLCA (specified in rtp) is
>>        connected by a bridging atom say Carbon. Do I need to create a
>>        new rtp entry for pdbgmx to work or is there  a work around by
>>        specifying that carbon as a separate residue ?
>>
>>
>>    The problem comes from this line in ffG45a3.rtp:
>>
>>     [ impropers ]
>>    ;  ai    aj    ak    al   gromos type
>>      C1    O5    -O    C2     gi_2
>>
>>    Clearly the force field is expecting to assign an improper around
>>    carbon C1 using an "O" atom in a previous unit as a reference.  I
>>    think this may be a typo in the file.  The ffG53a6.rtp file has this
>>    line for the same improper:
>>
>>      C1    O5    O1    C2     gi_2
>>
>>    I think this is what was intended.  I do not know why the anomeric
>>    carbon would be using a previous residue as a reference for
>>    assigning an improper.  Perhaps this is a bug.  Make a local copy of
>>    ffG45a3.rtp and fix the line to make it look like the ffG53a6.rtp
>>    entry.  Please report back if this works; it may need to be fixed
>>    for a future release.
>>
>>    -Justin
>>
>>
>>        Again thanks for replying.
>>
>>        Best,
>>        Vishal
>>
>>           -Justin
>>
>>               Your help is appreciated.
>>               Thanks,
>>               Vishal
>>
>>               On Sun, Feb 7, 2010 at 11:35 AM, Justin A. Lemkul
>>               <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>>        <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>>               <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>>        <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>> wrote:
>>
>>
>>
>>                  Vishal Agarwal wrote:
>>
>>                      Dear Mark,
>>
>>                      What I meant over here is the missing oxygen  (-O)
>>        which
>>               pdbgmx
>>                      complains about is not a part of .rtp entry. There
>>        is no such
>>                      type of oxygen specified in any of the .atp entry
>>        of the
>>                      forcefield I am using.
>>
>>
>>                  The "-O" is not an atom type, it indicates an oxygen
>>        atom of a
>>                  previous residue.  It is still not clear what it is
>> you're
>>               doing or
>>                  what the actual problem is. If you want a resolution,
>>        you'll
>>               have to
>>                  do as Mark asked and post your command line and the
>>        actual error
>>                  message.  Remember, you're asking for free help - you
>>        have to
>>               make
>>                  it easy for us to help you.
>>
>>                  -Justin
>>
>>                      Vishal
>>
>>
>>                      On Sun, Feb 7, 2010 at 4:54 AM, Mark Abraham
>>                      <Mark.Abraham at anu.edu.au
>>        <mailto:Mark.Abraham at anu.edu.au> <mailto:Mark.Abraham at anu.edu.au
>>        <mailto:Mark.Abraham at anu.edu.au>>
>>               <mailto:Mark.Abraham at anu.edu.au
>>        <mailto:Mark.Abraham at anu.edu.au> <mailto:Mark.Abraham at anu.edu.au
>>        <mailto:Mark.Abraham at anu.edu.au>>>
>>                      <mailto:Mark.Abraham at anu.edu.au
>>        <mailto:Mark.Abraham at anu.edu.au>
>>               <mailto:Mark.Abraham at anu.edu.au
>>        <mailto:Mark.Abraham at anu.edu.au>>
>>                      <mailto:Mark.Abraham at anu.edu.au
>>        <mailto:Mark.Abraham at anu.edu.au>
>>               <mailto:Mark.Abraham at anu.edu.au
>>        <mailto:Mark.Abraham at anu.edu.au>>>>> wrote:
>>
>>                         On 07/02/10 14:52, Vishal Agarwal wrote:
>>
>>                             Dear All,
>>
>>                             Can anyone help me how can I go about
>> preparing
>>               the topology
>>                             file for an
>>                             infinite crystal of cellulose. I have
>>        prepared the
>>               .gro
>>                      file for
>>                             5X5X5
>>                             unit cells of cellulose II using GROMACS
>>        utility and
>>                      intend to apply
>>                             periodic BC on it. It has a glucose molecule
>> as
>>               building
>>                      block
>>                             (GCLA).
>>                             When I try running pdbgmx, I get an error for
>>               extra hydrogens
>>                             (which is
>>                             not there in itp file but is actually there
>>        in the
>>               original
>>                             structure
>>                             which I am using) and missing oxygen (-O).
>>
>>
>>                         People who might help aren't at all interested
>>        in your
>>                      description
>>                         of the error message. If the contents of your head
>>               were reliable,
>>                         you wouldn't have seen the error in the first
>>        place,
>>               or would
>>                      have
>>                         solved the issue already. :-) Copy and paste
>>        your command
>>                      line, and
>>                         what seems to be the relevant part of the error.
>>
>>                         To use pdb2gmx, you need .rtp file entries that
>>               correspond to
>>                      your
>>                         monomers. If not, you will not be able to use
>>        pdb2gmx
>>               to generate
>>                         your topology files.
>>
>>                         Mark
>>                         --    gmx-users mailing list
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>>
>>                      --        Regards
>>
>>                      ***********************************************
>>                      Vishal Agarwal
>>                      Research Scholar
>>                      University of Massachusetts, Amherst
>>                      ***********************************************
>>                      'Your only obligation in any lifetime is to be true
>> to
>>               yourself."
>>                                 ---Richard Bach
>>
>>
>>                  --    ========================================
>>
>>                  Justin A. Lemkul
>>                  Ph.D. Candidate
>>                  ICTAS Doctoral Scholar
>>                  MILES-IGERT Trainee
>>                  Department of Biochemistry
>>                  Virginia Tech
>>                  Blacksburg, VA
>>                  jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu>
>>        <http://vt.edu> | (540)
>>
>>               231-9080
>>
>>                  http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>>
>>                  ========================================
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>>
>>               --        Regards
>>
>>               ***********************************************
>>               Vishal Agarwal
>>               Research Scholar
>>               University of Massachusetts, Amherst
>>               ***********************************************
>>               'Your only obligation in any lifetime is to be true to
>>        yourself."
>>                          ---Richard Bach
>>
>>
>>           --    ========================================
>>
>>           Justin A. Lemkul
>>           Ph.D. Candidate
>>           ICTAS Doctoral Scholar
>>           MILES-IGERT Trainee
>>           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
>>
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>>
>>        --        Regards
>>
>>        ***********************************************
>>        Vishal Agarwal
>>        Research Scholar
>>        University of Massachusetts, Amherst
>>        ***********************************************
>>        'Your only obligation in any lifetime is to be true to yourself."
>>                   ---Richard Bach
>>
>>
>>    --    ========================================
>>
>>    Justin A. Lemkul
>>    Ph.D. Candidate
>>    ICTAS Doctoral Scholar
>>    MILES-IGERT Trainee
>>    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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>>
>>
>> --
>> Regards
>>
>> ***********************************************
>> Vishal Agarwal
>> Research Scholar
>> University of Massachusetts, Amherst
>> ***********************************************
>> 'Your only obligation in any lifetime is to be true to yourself."
>>            ---Richard Bach
>>
>
> --
> ========================================
>
> 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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-- 
Regards

***********************************************
Vishal Agarwal
Research Scholar
University of Massachusetts, Amherst
***********************************************
'Your only obligation in any lifetime is to be true to yourself."
            ---Richard Bach
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