[gmx-users] Re: simulation of protein/water and phosphate ion

Mark Abraham Mark.Abraham at anu.edu.au
Thu Sep 29 05:50:20 CEST 2011


On 29/09/2011 9:59 AM, bharat gupta wrote:
> I repeated the nvt equilibration with 500 ps and it was successful , 
> after confirming the temperature graph. But during npt simulation, I 
> got the following error:-

You are rearranging the deck chairs on a ship that is already sinking. 
You've been given good advice from several people - see 
http://www.gromacs.org/Documentation/Terminology/Blowing_Up#Diagnosing_an_Unstable_System. 
There's nothing more to be said if you don't go and follow the advice 
there.  You've got a complex piece of machinery that isn't working for 
unknown reasons. Diagnosing what is wrong is hard, but only you have the 
information, motivation and resources to do it.

>
> step 131500, will finish Thu Sep 29 01:54:20 2011imb F  2%
> step 131520: Water molecule starting at atom 6981 can not be settled.
> Check for bad contacts and/or reduce the timestep if appropriate.
> Wrote pdb files with previous and current coordinates
>
> -------------------------------------------------------
> Program mdrun, VERSION 4.5.4
> Source code file: pme.c, line: 538
>
> Fatal error:
> 1 particles communicated to PME node 0 are more than 2/3 times the 
> cut-off out of the domain decomposition cell of their charge group in 
> dimension x.
> This usually means that your system is not well equilibrated.
>
>
> Since there are large no. of water molecules after 6981 , it means 
> that it is not happening because oh some interaction with phosphate ion. 

There is no correlation between atom number and geometric proximity to a 
suspect molecule. You have to go and look at the initial structure and 
the trajectory.

Mark

> What shall be done to rectify this ??
>
>
> On Wed, Sep 28, 2011 at 12:35 PM, Dallas Warren 
> <Dallas.Warren at monash.edu <mailto:Dallas.Warren at monash.edu>> wrote:
>
>     And where are these waters?  Close to the phosphate ions?
>
>     You really need to be asking more questions, looking at the
>     trajectory file / frames when it blows up, and determining what is
>     actually going on by yourself.
>
>     Catch ya,
>
>     Dr. Dallas Warren
>
>     Medicinal Chemistry and Drug Action
>
>     Monash Institute of Pharmaceutical Sciences, Monash University
>     381 Royal Parade, Parkville VIC 3010
>     dallas.warren at monash.edu <mailto:dallas.warren at monash.edu>
>
>     +61 3 9903 9304
>     ---------------------------------
>     When the only tool you own is a hammer, every problem begins to
>     resemble a nail.
>
>     *From:*gmx-users-bounces at gromacs.org
>     <mailto:gmx-users-bounces at gromacs.org>
>     [mailto:gmx-users-bounces at gromacs.org
>     <mailto:gmx-users-bounces at gromacs.org>] *On Behalf Of *bharat gupta
>     *Sent:* Wednesday, 28 September 2011 1:30 PM
>     *To:* Discussion list for GROMACS users
>     *Subject:* [gmx-users] Re: simulation of protein/water and
>     phosphate ion
>
>     it's showing error that certain atoms cannot be settled and these
>     atoms are of solvent molecules i.e. Water
>
>
>     On Wednesday, September 28, 2011, Dallas Warren
>     <Dallas.Warren at monash.edu <mailto:Dallas.Warren at monash.edu>> wrote:
>     > What is actually blowing up?  The protein or the phosphate
>     ions?  Do the phosphate ions run OK by themselves in water?
>     >
>     >
>     >
>     > Catch ya,
>     >
>     > Dr. Dallas Warren
>     >
>     > Medicinal Chemistry and Drug Action
>     >
>     > Monash Institute of Pharmaceutical Sciences, Monash University
>     > 381 Royal Parade, Parkville VIC 3010
>     > dallas.warren at monash.edu <mailto:dallas.warren at monash.edu>
>     >
>     > +61 3 9903 9304
>     > ---------------------------------
>     > When the only tool you own is a hammer, every problem begins to
>     resemble a nail.
>     >
>     >
>     >
>     > From: gmx-users-bounces at gromacs.org
>     <mailto:gmx-users-bounces at gromacs.org>
>     [mailto:gmx-users-bounces at gromacs.org
>     <mailto:gmx-users-bounces at gromacs.org>] On Behalf Of bharat gupta
>     > Sent: Wednesday, 28 September 2011 12:48 PM
>     > To: jalemkul at vt.edu <mailto:jalemkul at vt.edu>; Discussion list
>     for GROMACS users
>     > Subject: Re: [gmx-users] Re: simulation of protein/water and
>     phosphate ion
>     >
>     >
>     >
>     > Hi,
>     >
>     > I tried simulating the system again but this time with 2
>     phsophate ion and the charge of the system was neutralized by
>     adding 6 sodium ions . After minimizing , I equilibrated for 500
>     ps but I got "LINCS" error around 300ps.  It's happening due to
>     the addition of phosphate ions as I have simulated my protein in
>     water earlier without any problem. During nvt quilibration the
>     temperature coupling settings were for Protein and Non protein
>     groups. Do I have to make groups for Protein and water_ion. Please
>     comment??
>     >
>     > On Tue, Sep 27, 2011 at 7:09 PM, Justin A. Lemkul
>     <jalemkul at vt.edu <mailto:jalemkul at vt.edu>> wrote:
>     >
>     > bharat gupta wrote:
>     >
>     > HI,
>     >
>     > I have tried simulating my protein (GFP) solvated with water
>     molecules and 10 phosphate ions. During the md run step the system
>     starts exploding after  500 ps. What could be the reason for this
>     . I know this is happening due to the addition of phosphate ion
>     but I need to study the binding of ions . So, what shall I do ??
>     >
>     >
>     >
>     >
>     http://www.gromacs.org/Documentation/Terminology/Blowing_Up#Diagnosing_an_Unstable_System
>     >
>     > -Justin
>     >
>     > --
>     > ========================================
>     >
>     > 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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>     > --
>     > Bharat
>     > Ph.D. Candidate
>     > Room No. : 7202A, 2nd Floor
>     > Biomolecular Engineering Laboratory
>     > Division of Chemical Engineering and Polymer Science
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>     >
>     >
>
>     -- 
>     Bharat
>     Ph.D. Candidate
>     Room No. : 7202A, 2nd Floor
>     Biomolecular Engineering Laboratory
>     Division of Chemical Engineering and Polymer Science
>     Pusan National University
>     Busan -609735
>     South Korea
>     Lab phone no. - +82-51-510-3680, +82-51-583-8343
>
>     Mobile no. - 010-5818-3680
>     E-mail : monu46010 at yahoo.com <mailto:monu46010 at yahoo.com>
>
>
>     --
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>
>
>
> -- 
> Bharat
> Ph.D. Candidate
> Room No. : 7202A, 2nd Floor
> Biomolecular Engineering Laboratory
> Division of Chemical Engineering and Polymer Science
> Pusan National University
> Busan -609735
> South Korea
> Lab phone no. - +82-51-510-3680, +82-51-583-8343
> Mobile no. - 010-5818-3680
> E-mail : monu46010 at yahoo.com <mailto:monu46010 at yahoo.com>
>
>
>

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