[gmx-users] Error:EM did not converge while using polarizable ion

[Justin Lemkul]

On 7/31/15 7:15 PM, 折晓会 wrote:
> Dear all,
>
> I am now trying to simulation polarizable LiCl solutions with Gromacs 5.0.5, where SWM4-NDP water model and corresponding polarizable ion model are used. The force field files come from professor Spoel and can be found in the website http://virtualchemistry.org/pol.php.
>
> During the simulation, error occurs:
>
> step 63: EM did not converge in 100 iterations, RMS force 159.892
> step 64: EM did not converge in 100 iterations, RMS force 542.311
> step 65: EM did not converge in 100 iterations, RMS force 1064.542
> step 66: EM did not converge in 100 iterations, RMS force 1168.229
> step 67: EM did not converge in 100 iterations, RMS force 853.824
> step 68: EM did not converge in 100 iterations, RMS force 842.719
> step 69: EM did not converge in 100 iterations, RMS force 1211.043
> step 70: EM did not converge in 100 iterations, RMS force 2015.682
> step 71: EM did not converge in 100 iterations, RMS force 2926.036
> step 72: EM did not converge in 100 iterations, RMS force 3314.541
> step 73: EM did not converge in 100 iterations, RMS force 4813.701
> step 74: EM did not converge in 100 iterations, RMS force 9258.925
> step 76: EM did not converge in 100 iterations, RMS force 1761.227
> step 77: EM did not converge in 100 iterations, RMS force 589.506
> Segmentation fault (core dumped)
>
> I also try to simulate the pure water with SWM4-NDP model, and it works well. I am wondering if anyone can help me. I failed to find answers on Google and am stuck here for a long time.
>
> The force field for ions are as follows:
>
> ; Lithium, Li+
> [ moleculetype ]
> ; molname    nrexcl
> Li        1
>
> [ atoms ]
> ; id    at type    res nr    residu name    at name    cg nr    charge
> 1    Lic    1    Li        Lic1    1     1.3104270
> 2    Lis    1    Li        Lis1    1    -0.3104270
>
> [ polarization ]
> ; See notes above.    alpha (nm^3)
> 1    2    1     0.000032
>
>
> ; Chloride, Cl-
> [ moleculetype ]
> ; molname    nrexcl
> Cl        1
>
> [ atoms ]
> ; id    at type    res nr    residu name    at name    cg nr    charge
> 1    Clc    1    Cl        Clc1    1     2.4571870
> 2    Cls    1    Cl        Cls1    1    -3.4571870
>
> [ polarization ]
> ; See notes above.    alpha (nm^3)
> 1    2    1     0.003969
>
>
> Any help will be appreciated!
>

Can you provide the contents of your .mdp file?  What was the outcome of energy 
minimization prior to starting this run?

-Justin

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

Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

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