[gmx-users] Re: A note while running grompp for nvt equilibration

Anu Chandran miscofanu at gmail.com
Fri Feb 22 05:38:17 CET 2013


Thanks a lot of suggestions. Now my simulation is running without any
errors.
I have decreased the box dimension (by using -d 1.2 in editconf) and also
by using cutoff with
rlist=rvdw=rcoulomb=1.0. Now there is no warning or errors in nvt and npt
equilibration.

Thank you,

with regards,
Anu

On Thu, Feb 21, 2013 at 10:32 AM, Emanuel Birru <Emanuel.Birru at monash.edu>wrote:

>
> Correction on #6
> 6. if that doesn't help decrease your time step.
> Sorry for the confusion :)
>
> Cheers,
> EB
> -----Original Message-----
> From: gmx-users-bounces at gromacs.org [mailto:gmx-users-bounces at gromacs.org]
> On Behalf Of Anu Chandran
> Sent: Thursday, 21 February 2013 3:34 PM
> To: Discussion list for GROMACS users
> Subject: Re: [gmx-users] Re: A note while running grompp for nvt
> equilibration
>
> Sir,
> I tried using cutoff for van der Waals interactions. I got the following
> error during the nvt equilibration:
>
>
> "step 0, time 0 (ps)  LINCS WARNING
> relative constraint deviation after LINCS:
> rms 0.040332, max 2.236585 (between atoms 24073 and 24072) bonds that
> rotated more than 30 degrees:
>  atom 1 atom 2  angle  previous, current, constraint length Wrote pdb
> files with previous and current coordinates
>
> Step 0, time 0 (ps)  LINCS WARNING
> relative constraint deviation after LINCS:
> rms 0.005594, max 0.252567 (between atoms 24347 and 24344) bonds that
> rotated more than 30 degrees:
>  atom 1 atom 2  angle  previous, current, constraint length
>   24349  24347   34.7    0.1517   0.1322      0.1250
>   24383  24381   39.0    0.2108   0.1438      0.1340
>   24382  24381   31.8    0.1027   0.1089      0.1010
>   24387  24383   32.0    0.2041   0.1399      0.1340
>   24388  24387   30.3    0.2493   0.1070      0.1010
>   24344  24342   54.8    0.2383   0.1843      0.1529
>   24347  24344   49.3    0.2560   0.1906      0.1522
>   24346  24344   50.0    0.2082   0.1295      0.1090
>   24345  24344   56.2    0.1728   0.1357      0.1090
>   24063  24061   34.7    0.2181   0.1461      0.1335
>   24072  24063   39.2    0.1828   0.1480      0.1449
> starting mdrun 'Protein in water'
> 50000 steps,    100.0 ps.
>
> Step 0, time 0 (ps)  LINCS WARNING
> relative constraint deviation after LINCS:
> rms 9.003327, max 419.005005 (between atoms 24380 and 24378) bonds that
> rotated more than 30 degrees:
>  atom 1 atom 2  angle  previous, current, constraint length
>   24381  24378   97.3    0.1825  59.6595      0.1463
>   24380  24378  122.0    0.1260  45.7805      0.1090
>   24379  24378  111.1    0.1319  28.6967      0.1090
>   24073  24072   90.2    0.3528   0.8138      0.1090
>   24349  24347   89.7    0.1517  46.2536      0.1250
>   24348  24347   95.7    0.1756  13.5872      0.1250
>   24383  24381   86.4    0.2108   5.1830      0.1340
>   24382  24381  105.2    0.1027   2.7271      0.1010
>   24387  24383   85.2    0.2041   2.1027      0.1340
>   24384  24383   88.3    0.0874   2.5321      0.1340
>   24386  24384   92.8    0.1068   3.6505      0.1010
>   24385  24384   88.0    0.0997   3.7036      0.1010
>   24389  24387   88.7    0.2448   1.5454      0.1010
>   24388  24387   88.4    0.2493   1.5186      0.1010
>   24368  24366   74.3    0.1338   0.2409      0.1335
>   24367  24366  104.8    0.1231   0.0883      0.1229
>   24370  24368  103.0    0.1458   5.0355      0.1449
>   24369  24368   96.3    0.1012   0.2541      0.1010
>  24390  24370  121.9    0.1532   4.8700      0.1522
>   24371  24370   97.9    0.1097   5.0227      0.1090
>   24375  24372   80.9    0.1936   9.2201      0.1529
>   24374  24372   92.0    0.1124   1.9509      0.1090
>   24373  24372   86.1    0.1124   1.8518      0.1090
>   24378  24375   99.7    0.1500  49.8084      0.1529
>   24377  24375   86.5    0.1471  16.9457      0.1090
>   24376  24375   87.1    0.1476  15.3512      0.1090
>   24392  24390   71.6    0.1338   0.2163      0.1335
>   24391  24390   72.8    0.1231   0.3302      0.1229
>   24394  24392  152.1    0.1450   0.1137      0.1449
>   24393  24392  121.6    0.1011   0.1883      0.1010
>   24414  24394   32.9    0.1523   0.1900      0.1522
>   24396  24394   33.8    0.1529   0.1910      0.1529
>   24395  24394   40.7    0.1090   0.1519      0.1090
>   24342  24340  133.3    0.1870   0.5324      0.1449
>   24350  24342   80.5    0.1906   0.6983      0.1522
>   24344  24342   85.5    0.2383   4.0017      0.1529
>   24343  24342   90.9    0.1423   0.6476      0.1090
>   24347  24344  104.1    0.2560  11.9267      0.1522
>   24346  24344   81.7    0.2082   3.4103      0.1090
>   24345  24344   82.9    0.1728   4.6679      0.1090
>   24354  24352   38.4    0.1465   0.1761      0.1449
>   24366  24354   54.4    0.1527   0.0985      0.1522
>   24063  24061   31.1    0.2181   0.1464      0.1335
>   24072  24063   30.6    0.1828   0.1463      0.1449
>   24068  24066   46.3    0.1202   0.1123      0.1090
>   24067  24066   44.6    0.1209   0.1131      0.1090
>   24070  24069   92.8    0.0417   0.1386      0.1090
>
> step 0: Water molecule starting at atom 395505 can not be settled.
> Check for bad contacts and/or reduce the timestep if appropriate.
> wrote pdb files with previous and current coordinates step 0
> Warning: 1-4 interaction between 24378 and 24384 at distance 61.758 which
> is larger than the 1-4 table size 2.000 nm These are ignored for the rest
> of the simulation This usually means your system is exploding, if not, you
> should increase table-extension in your mdp file or with user tables
> increase the table size
> ------------------------------------------------------
> Program mdrun, VERSION 4.5.3
> Source code file: pme.c, line: 534
>
> Fatal error:
> 5 particles communicated to PME node 2 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."
>
>
> Thank You,
>
> regards,
> Anu
>
>
>
>
> On Tue, Feb 19, 2013 at 6:26 PM, Justin Lemkul <jalemkul at vt.edu> wrote:
>
> >
> >
> > On 2/19/13 1:36 AM, Anu Chandran wrote:
> >
> >> Sir,
> >> Thank you for the reply. As per the suggestion, I tried increasing
> >> the rlist. Note or warning stopped when rlist was increased to 1.8.
> >> Also with this value of rcoulomb, the box size also needs to be
> >> increased. I would like to know whether it is fine to keep rlist 1.8
> >> and also whether there is any other alternative rather than
> >> increasing rlist since increase in rlist requires an increase in box
> >> size.
> >>
> >
> > I would investigate why you have such large charge groups.  For a
> > protein in water (which is what you appear to have based on the .mdp
> > file), you should not have such large charge groups.  Haphazardly
> > adjusting cutoffs can have a negative effect on the simulation.
> > Increasing rlist may result in poorer performance.  Why are you using
> > a switching potential for van der Waals interactions?  Exact
> > specifications for OPLS are hard to come by in the literature, but most
> commonly one sees:
> >
> > rvdw = 1.0
> > vdwtype = cutoff
> > rlist = 1.0
> > rcoulomb = 1.0
> > coulombtype = PME
> >
> > -Justin
> >
> >
> >  Thank you,
> >> with regards
> >> Anu
> >>
> >> On Fri, Feb 15, 2013 at 5:28 PM, Dr. Vitaly Chaban
> >> <vvchaban at gmail.com
> >> >wrote:
> >>
> >>  I am tyring to do a simulation of a monomer and an octamer of the
> >> same
> >>>> molecule
> >>>> using gromacs 4.5.3 with opls force field. Monomer simulations ran
> >>>> with
> >>>>
> >>> out
> >>>
> >>>> any note or
> >>>> warning, but when i tried to do nvt equilibration for the octamer,
> >>>> i got
> >>>>
> >>> the
> >>>
> >>>> following note while running grompp
> >>>>
> >>>> "NOTE 1 [file nvt.mdp]:
> >>>>    The sum of the two largest charge group radii (0.779095) is
> >>>> larger than
> >>>>    rlist (1.400000) - rvdw (1.000000)"
> >>>> The mdp file used is as follows:
> >>>>
> >>>> define                  = -DPOSRES
> >>>> integrator              = md
> >>>> dt                      = 0.002
> >>>> nsteps                  = 50000
> >>>> nstcomm                 = 10
> >>>> nstxout                 = 100
> >>>> nstvout                 = 100
> >>>> nstlog                  = 100
> >>>> nstenergy               = 100
> >>>> nstlist                 = 5
> >>>> ns_type                 = grid
> >>>> pbc                     = xyz
> >>>> rlist                   = 1.4
> >>>> coulombtype             = PME
> >>>> rcoulomb                = 1.4
> >>>> epsilon_r               = 1
> >>>> vdwtype                 = Switch
> >>>> rvdw_switch             = 0.9
> >>>> rvdw                    = 1.00
> >>>> fourierspacing          = 0.12
> >>>> pme_order               = 4
> >>>> ewald_rtol              = 1e-5
> >>>> optimize_fft            = yes
> >>>> Tcoupl                  = nose_hoover
> >>>> tc_grps                 = Protein  Non-Protein
> >>>> tau_t                   = 0.4      0.4
> >>>> ref_t                   = 300      300
> >>>> nh-chain-length         = 1
> >>>> pcoupl                  = no
> >>>> gen_vel                 = yes
> >>>> gen_temp                = 300.0
> >>>> gen_seed                = 1984
> >>>> continuation             = no
> >>>> constraints              = all-bonds
> >>>> constraint-algorithm     = LINCS
> >>>> lincs-order              = 4
> >>>> lincs-iter               = 1
> >>>> lincs-warnangle          = 30
> >>>>
> >>>>
> >>>> Can anybody please help me on how to go about with it?
> >>>>
> >>>
> >>>
> >>> 1) Increase RLIST
> >>> 2) Re-distribute atoms among charge groups so that to make charge
> >>> groups [spatially] smaller.
> >>>
> >>>
> >>>
> >>> Dr. Vitaly V. Chaban
> >>> MEMPHYS - Center for Biomembrane Physics Department of Physics,
> >>> Chemistry and Pharmacy University of Southern Denmark Campusvej 55,
> >>> 5230 Odense M, Denmark
> >>> --
> >>> gmx-users mailing list    gmx-users at gromacs.org
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> >>>
> > --
> > ==============================**==========
> >
> > Justin A. Lemkul, Ph.D.
> > Research Scientist
> > Department of Biochemistry
> > Virginia Tech
> > Blacksburg, VA
> > jalemkul[at]vt.edu | (540) 231-9080
> > http://www.bevanlab.biochem.**vt.edu/Pages/Personal/justin<http://www.
> > bevanlab.biochem.vt.edu/Pages/Personal/justin>
> >
> > ==============================**==========
> >
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