[gmx-users] How to efficiently fix pbc trajectories problems for VMD using

Mon May 19 23:28:01 CEST 2014

On 5/19/14, 12:29 PM, Vito Genna wrote:
> Dear Mark,
>
> You can see the results of -pbc whole and -pbc nojump on this pics http://wikisend.com/download/777550/PICs.zip
> I tried to use the flag -s with the .tpr and then with the .gro file but in both cases I obtain a result similar to that one shown on
> PICs on link. A broken system.
> Both .tpr and .gro used for the -pbc whole/nojumo/fit are ok and the system is complete.During the equillibration and for the first ~20ns of production phase
> the system is stable within the box. The problem start to appear as soon as the system leaves the first box (~25ns)
>

Can you post an image looking straight-on at the system, with box vectors 
rendered, with and without water?  The oblique shots you've provided are a bit 
hard to interpret.

I've dealt with very complex systems like these (multiple proteins + dsDNA + 
ions + ligands) and it is a pain.  I believe I went through 6 rounds of trjconv 
for most of them (hundreds of ns in length).  The exact protocol is highly 
system-specific, but the key is that it is often necessary to use custom index 
groups (a specific residue, or a few in some key location) for centering and/or 
fitting.

-Justin

> Thanks in advance
>
> V
>
> Vito Genna, PhD-Fellow
> Italian Institute of Technology
> Drug Discovery and Development department
> Via Morego 30, 16163 Genoa, Italy
>
> -------------------------------------------------------------------------------------------------------------
> The process of scientific discovery is, in effect, a continual flight from wonder.
> Albert Einstein
>
>
> ________________________________________
> From: gromacs.org_gmx-users-bounces at maillist.sys.kth.se [gromacs.org_gmx-users-bounces at maillist.sys.kth.se] on behalf of Mark Abraham [mark.j.abraham at gmail.com]
> Sent: Monday, May 19, 2014 5:32 PM
> To: Discussion list for GROMACS users
> Subject: Re: [gmx-users] How to efficiently fix pbc trajectories problems for VMD using
>
> On Mon, May 19, 2014 at 5:03 PM, Vito Genna <Vito.Genna at iit.it> wrote:
>
>> Dear Mark,
>>
>> Thank you for you prompt reply.
>> Yes, indeed I was following the suggested trjconv workflow. Right you are.
>> When I say "does not work" I mean that the system is stretched between two
>> adjacent boxes showing internal bonds that run throughout the "main" pbc
>> box (extremely long).
>>
>> Regarding the steps:
>> Yes I already visualized the results step by step and after the 1) one
>> trjconv fixes the bond problems but splits my protein in two distinct part
>> (the protein contains only 1 chain) moving them in two boxes.
>>
>
> Sounds like you mean trjconv from your 1)a). Please be specific. If so,
> IIRC, -pbc whole restores the "wholeness" as it judges from state of the -s
> input. So if you made the .tpr from a .gro file that had the protein in two
> chunks across periodic boundaries from the equilibration, so will the
> output be split. This was what I guessed before, but you didn't report
> whether you investigated whether your .tpr file contained what you think it
> does. IIRC you can also use a coordinate file for -s for that stage, since
> "-pbc whole" does not actually use the topology, and it is easier to
> construct a .gro file that looks how you want.
>
> Mark
>
> At this point I use the -pbc nojump option that gives me the same previous
>> problem (bond excessively long).
>>
>> If I could reassembly the protein after -pbc whole action I'll be
>> completely satisfied.
>>
>> Any suggestion?
>>
>> Thank in advance.
>>
>> Cheers
>>
>> Vito Genna, PhD-Fellow
>> Italian Institute of Technology
>> Drug Discovery and Development department
>> Via Morego 30, 16163 Genoa, Italy
>>
>>
>> -------------------------------------------------------------------------------------------------------------
>> The process of scientific discovery is, in effect, a continual flight from
>> wonder.
>> Albert Einstein
>>
>>
>> ________________________________________
>> From: gromacs.org_gmx-users-bounces at maillist.sys.kth.se [
>> gromacs.org_gmx-users-bounces at maillist.sys.kth.se] on behalf of Mark
>> Abraham [mark.j.abraham at gmail.com]
>> Sent: Monday, May 19, 2014 4:31 PM
>> To: Discussion list for GROMACS users
>> Subject: Re: [gmx-users] How to efficiently fix pbc trajectories problems
>> for VMD using
>>
>> You seem to be following
>>
>> http://www.gromacs.org/Documentation/Terminology/Periodic_Boundary_Conditions
>> ,
>> which is good. But it's hard to help when we don't know what you think
>> "doesn't work" means. Make sure that the things you think are whole in
>> md_0_1.tpr actually are. Visualize your intermediate stages of 1) to see
>> where the issue arises. If you need to, upload some pictures to a file
>> sharing service that show what the input and unsatisfactory output was.
>>
>> Mark
>>
>> On Mon, May 19, 2014 at 3:15 PM, Vito Genna <Vito.Genna at iit.it> wrote:
>>
>>> Hi to everybody,
>>>
>>> My name is Vito and I would like to share with you (and discuss also) the
>>> problems that I have found during my TRJs analysis.
>>> I have a system made by: Protein + dsDNA + Ligand. I obtained my single
>>> precision trajectory in a .xtc file.
>>> Well, I'd like to analyze my TRJs using VMD due to its intrinsic velocity
>>> in calcuating (Distances, angles, RMSD and so on) but I cannot do it
>>> because I encounter a serious issue with the visualization (pbc problems
>> as
>>> you surely know)
>>> To try to avoid the problem I've used several protocols, without success:
>>>
>>> 1)
>>>
>>> a) trjconv_mpi -f md_0_1.part0001.xtc -o md_0_1-whole.xtc -s md_0_1.tpr
>>> -pbc whole (on the entire system)
>>> b) trjconv_mpi -f md_0_1-whole.xtc -o md_0_1-nojump.xtc -s md_0_1.tpr
>> -pbc
>>> nojump
>>> (on the entire system)
>>> c) trjconv_mpi -f md_0_1-nojump.xtc -o md_0_1-fit.xtc -s md_0_1.tpr -fit
>>> progressive (on Protein only)
>>>
>>> It does not work.
>>>
>>> 2)
>>>
>>> a) trjconv_mpi -f (as the previous one) -pbc mol -ur compact -center -o
>>> compact.xtc
>>>
>>> It does not work as well.
>>>
>>> 3) Option 2 changing the flag -pbc mol with -pbc res
>>>
>>> It does not work.
>>>
>>> New idea? New possible combo?
>>>
>>> Thanks in advance for your replies.
>>>
>>> All the best
>>>
>>> Vito
>>>
>>>
>>>
>>>
>>> Vito Genna, PhD-Fellow
>>> Italian Institute of Technology
>>> Drug Discovery and Development department
>>> Via Morego 30, 16163 Genoa, Italy
>>>
>>>
>>>
>> -------------------------------------------------------------------------------------------------------------
>>> The process of scientific discovery is, in effect, a continual flight
>> from
>>> wonder.
>>> Albert Einstein
>>>
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-- 
==================================================

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

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