[gmx-users] links warnangles

vferrario at units.it vferrario at units.it
Wed Feb 2 14:33:14 CET 2011


I've just tried with a single CHCL3 molecule, here's the output:

Back Off! I just backed up md.log to ./#md.log.2#
Getting Loaded...
Reading file clfmin.tpr, VERSION 4.0.7 (single precision)
Loaded with Money

NNODES=2, MYRANK=1, HOSTNAME=biohazard
NODEID=1 argc=6
Making 1D domain decomposition 2 x 1 x 1

Step -1, time -0.001 (ps)  LINCS WARNING
relative constraint deviation after LINCS:
rms 301.323604, max 324.810791 (between atoms 1 and 3)
bonds that rotated more than 90 degrees:
  atom 1 atom 2  angle  previous, current, constraint length

Back Off! I just backed up step-1b_n1.pdb to ./#step-1b_n1.pdb.2#

Back Off! I just backed up step-1c_n1.pdb to ./#step-1c_n1.pdb.2#
Wrote pdb files with previous and current coordinates

Back Off! I just backed up traj.trr to ./#traj.trr.1#

Back Off! I just backed up ener.edr to ./#ener.edr.2#
Steepest Descents:
    Tolerance (Fmax)   =  2.50000e+00
    Number of steps    =       100000
Step=    0, Dmax= 1.0e-02 nm, Epot=  0.00000e+00 Fmax= 0.00000e+00, atom= 0

writing lowest energy coordinates.

Back Off! I just backed up clfmin.gro to ./#clfmin.gro.1#

Steepest Descents converged to Fmax < 2.5 in 1 steps
Potential Energy  =  0.0000000e+00
Maximum force     =  0.0000000e+00 on atom 0
Norm of force     =  0.0000000e+00

NOTE: 7 % of the run time was spent communicating energies,
       you might want to use the -nosum option of mdrun


gcq#320: "Do You Have Sex Maniacs or Schizophrenics or Astrophysicists  
in Your Family?" (Gogol Bordello)

The minimum is reached without steps, so... I don't know if the single  
atom minimization wors or not...

Valerio



"Justin A. Lemkul" <jalemkul at vt.edu> ha scritto:

>
>
> vferrario at units.it wrote:
>> Dear all,
>> I'm dealing with a simulation of a polymer in CHCL3, the polymer  
>> works good, but I have some problems with the CHCL3 definition in  
>> GROMOS 53a6 ff.
>> I've taken the CHCL3 definition from the automated topology builder website:
>>
>> http://compbio.biosci.uq.edu.au/atb/download.py?molid=1597&file=itp_uniatom
>>
>> So the itp file of my CHCL3 definition is:
>>
>> [ moleculetype ]
>> ; Name            nrexcl
>> CLF             3
>>
>> [ atoms ]
>> ;   nr       type  resnr residue  atom   cgnr     charge       mass  
>>  typeB    chargeB      massB
>>     1        CCL      1    CLF    CCl      1      0.179     12.011   
>>  ; qtot 0.179
>>     2        HCL      1    CLF    HCl      1      0.082      1.008   
>>  ; qtot 0.261
>>     3       CLCL      1    CLF    CL1      1     -0.087     35.453   
>>  ; qtot 0.174
>>     4       CLCL      1    CLF    CL2      1     -0.087     35.453   
>>  ; qtot 0.087
>>     5       CLCL      1    CLF    CL3      1     -0.087     35.453   
>>  ; qtot 0
>>
>> [ constraints ]
>>    1     3     1     0.1758
>>    1     4     1     0.1758
>>    1     5     1     0.1758
>>    2     3     1     0.233839
>>    2     4     1     0.233839
>>    2     5     1     0.233839
>>    3     4     1     0.290283
>>    3     5     1     0.290283
>>    4     5     1     0.290283
>>
>> I've generated a box of solvent, but when I try to minimize it with  
>> the following mdp file:
>>
>> title                = Minimization
>> cpp                = /lib/cpp
>> include                = -I../top
>> constraints             = none
>> integrator            = steep
>> emtol                = 2.5
>> emstep                  = 0.01
>> nsteps                = 100000
>> nbfgscorr               = 10
>> nstenergy            = 100
>> nstxtcout            = 0
>> xtc_grps            = system
>> energygrps            = system
>> nstlist                = 5
>
> For EM, nstlist should be 1.
>
>> ns_type                = grid
>> pbc                     = xyz
>> rlist                = 1.0
>> coulombtype            = cut-off
>
> Plain cutoffs lead to bad artifacts and thus should generally not be used.
>
>> rcoulomb            = 1.0
>> vdwtype                 = cut-off
>> rvdw                = 1.4
>> fourierspacing            = 0.15
>> fourier_nx              = 0
>> fourier_ny              = 0
>> fourier_nz              = 0
>> pme_order               = 4
>> optimize_fft            = yes
>> tcoupl                  = no
>> pcoupl                  = no
>> gen_vel                 = no
>> constraint_algorithm    = LINCS
>> lincs_order             = 8
>> lincs_iter              = 2
>> nstlog                  = 100
>> lincs_warnangle         = 90
>>
>> The system crash giving me the following error:
>>
>> Fatal error:
>> Too many LINCS warnings (1413)
>> If you know what you are doing you can adjust the lincs warning  
>> threshold in your mdp file
>> or set the environment variable GMX_MAXCONSTRWARN to -1,
>> but normally it is better to fix the problem
>>
>> My question is: why the system crash and why LINCS warnings are  
>> generated if all the molecule is constrained? What shell I do to  
>> avoid these probles? New CHCL3 definition?
>
> The charges and atom types match exactly what the force field  
> prescribes, so those are probably solid.
>
> You need to simplify the problem.  You built a box, but it is  
> failing.  Does an EM of a single molecule work, or does it fail as  
> well?  Consult the following:
>
> http://www.gromacs.org/Documentation/Terminology/Blowing_Up#Diagnosing_an_Unstable_System
>
> -Justin
>
>> Please help me, thank you in advance.
>>
>> Valerio
>>
>>
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>>
>>
>
> -- 
> ========================================
>
> 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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