[gmx-users] genion doubt

Justin A. Lemkul jalemkul at vt.edu
Sat May 15 17:50:58 CEST 2010



Bharath.K. Chakravarthi wrote:
> HI....
> I'm not sure about this kind of error but as per my knowledge the 
> problem might be with the parameter cpp in mdp file.
> In my mdp file it is as follows
> 

The problem is unrelated to cpp, since the error complained about the use of 
"warnings" in the .mdp file.  Further, if we are to assume Gromacs 4.0.x, the 
cpp setting is ignored, as Gromacs has its own C pre-processor now.

> title = ecoli_nusG
> cpp = /usr/bin/cpp
> define = -DPOSRES
> constraints = all-bonds
> integrator = md
> dt = 0.001 ; ps !
> nsteps = 100000 ; total 100 ps.
> nstcomm = 1
> ..
> ..
> 
> and somewhere i read the nsteps should be between 50000-100000 for pr 
> dynamics.....

In general, yes, to obtain good equilibration you would certainly want to run 
for more than 1.0 ps, but I would say there is no absolute setting that should 
be applied.

-Justin

> search gromacs tutorial for better clue... 
> 
> On Sat, May 15, 2010 at 6:03 AM, manjula kasinathan <manjubfs at gmail.com 
> <mailto:manjubfs at gmail.com>> wrote:
> 
> 
>     hi snip
> 
>             Thank u. as per ur suggestion i added sodium ions to my
>     protein. then i carried out mdrun for energy minimization nsteps
>     3000 but i runs only for 1108 steps. then i went to position
>     restrain steps the command i gave
> 
>             grompp -f pr.mdp -c em.gro -p top.top -o pr.tpr
> 
>     i got a fatal error
>                 Too many warnings (1), grompp terminated.
>                 If you are sure all warnings are harmless, use the
>     -maxwarn option
> 
>     WARNING 1 [file pr.mdp, line unknown]:
>       Unknown or double left-hand 'warnings' in parameter file
> 
>     y i'm getting this error.how can i correct this could any one help plz.
> 
>     my pr.mdp file
> 
>     title               = FWS
>     warnings            = 10
>     cpp                 = /usr/local/gromacs/share/gromacs/cpp
>     define              = -DPOSRES
>     constraints         = all-bonds
>     integrator          = md
>     dt                  = 0.002 ; ps !
>     nsteps              = 500 ; total 1.0 ps.
>     nstcomm             = 1
>     nstxout             = 250     ; collect data every 0.5 ps
>     nstvout             = 1000
>     nstfout             = 0
>     nstlog              = 10
>     nstenergy           = 10
>     nstlist             = 10
>     ns_type             = grid
>     rlist               = 1.0
>     coulombtype         = PME
>     rcoulomb            = 1.0
>     vdwtype             = cut-off
>     rvdw                = 1.4
>     fourierspacing      = 0.12
>     fourier_nx          = 0
>     fourier_ny          = 0
>     fourier_nz          = 0
>     pme_order           = 4
>     ewald_rtol          = 1e-5
>     optimize_fft        = yes
>     ; Berendsen temperature coupling is on
>     Tcoupl              = v-rescale
>     tau_t               = 0.1     0.1
>     tc-grps             = protein non-protein
>     ref_t               = 300     300
>     ; Pressure coupling is on
>     Pcoupl              = parrinello-rahman
>     Pcoupltype          = isotropic
>     tau_p               = 0.5
>     compressibility     = 4.5e-5
>     ref_p               = 1.0
>     ; Generate velocites is on at 300 K.
>     gen_vel             = yes
>     gen_temp            = 300.0
>     gen_seed            = 173529
> 
>     with this warnings i proceeded with mdrun but i get the following
>     LINCS warnnings
> 
>     starting mdrun 'Protein in water'
>     500 steps,      1.0 ps.
>     step 300, will finish Sat May 15 08:57:23 2010
>     Step 394, time 0.788 (ps)  LINCS WARNING
>     relative constraint deviation after LINCS:
>     rms 0.000103, max 0.001028 (between atoms 4478 and 4480)
>     bonds that rotated more than 30 degrees:
>      atom 1 atom 2  angle  previous, current, constraint length
>        4478   4480   33.4    0.1081   0.1091      0.1090
>     Step 423, time 0.846 (ps)  LINCS WARNING
>     relative constraint deviation after LINCS:
>     rms 0.442275, max 40.666431 (between atoms 8211 and 8212)
>     bonds that rotated more than 30 degrees:
>      atom 1 atom 2  angle  previous, current, constraint length
>        8473   8476   88.6    0.1527   0.2741      0.1522
>        8473   8475   89.9    0.1094   3.6185      0.1090
>        8473   8474   89.5    0.1094   0.2778      0.1090
>        8471   8473   87.2    0.1455   0.2548      0.1449
>        8471   8472   33.2    0.1013   0.1241      0.1010
>        8215   8217   32.8    0.1090   0.1240      0.1090
>        8215   8216   39.2    0.1091   0.1282      0.1090
>        8211   8215   45.8    0.1536   0.1603      0.1529
>        8211   8213   44.0    0.1425   0.1645      0.1410
>        8211   8212   90.2    0.4225   4.5416      0.1090
>        8209   8211   45.6    0.1511   0.1348      0.1529
>        8209   8210   32.4    0.1098   0.1199      0.1090
>        8207   8209   33.3    0.1482   0.1823      0.1449
>        7224   7225   30.4    0.1013   0.1010      0.1010
>        5296   5297   30.5    0.1093   0.1092      0.1090
>     Warning: 1-4 interaction between 8208 and 8213 at distance 4.720
>     which is larger than the 1-4 table size 2.400 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
> 
>     Step 424, time 0.848 (ps)  LINCS WARNING
>     relative constraint deviation after LINCS:
>     rms 171806.092017, max 19412182.000000 (between atoms 8235 and 8236)
>     bonds that rotated more than 30 degrees:
>      atom 1 atom 2  angle  previous, current, constraint length
>        8507   8508   90.0    0.1011   0.2179      0.1010
>        8497   8499   39.8    0.1460   0.2065      0.1449
>        8497   8498   59.8    0.1009   0.1923      0.1010
>        8495   8497   44.0    0.1354 729.7847      0.1335
>        8495   8496   94.4    0.1235 729.7617      0.1229
>        8491   8493   89.7    0.1091   0.2077      0.1090
>        8487   8489   89.8    0.1091   0.5344      0.1090
>        8485   8491   32.7    0.1531   0.1890      0.1529
>        8485   8486   47.4    0.1091   0.1421      0.1090
>        8482   8485   50.7    0.1536 215.0330      0.1529
>        8482   8484   71.0    0.1094 214.9777      0.1090
>        8482   8483   92.6    0.1091 215.0566      0.1090
>        8480   8495   77.1    0.1633 417.3555      0.1522
>        8480   8482   84.2    0.1556 871.1644      0.1529
>        8480   8481   80.7    0.1078 911.5953      0.1090
>        8478   8480   43.4    0.1559 3067.7700      0.1449
>        8478   8479   92.3    0.1070 3786.8391      0.1010
>      
>     t = 0.848 ps: Water molecule starting at atom 80338 can not be settled.
>     Check for bad contacts and/or reduce the timestep.
>     Wrote pdb files with previous and current coordinates
> 
>     could any one help me to overcome this problem. thanks in advance
> 
>     hi justin as per ur suggestion i viewed my structure but there is no
>     clash in it.
>     y i'm getting this error?????
> 
>     Cheers,
>     Manju
> 
>      
> 
> 
> 
>     -- 
>     With Regards,
> 
>     Manjulakasinathan
> 
>     --
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> 
> 
> 
> -- 
> Bharath.K.Chakravarthi
> Post Graduate Student
> Kuvempu University
> Shimoga
> Karnataka
> Ph:9535629260
> 

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

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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