[gmx-users] LINCS warning during energy minimization of nitrogen with virtual site

Ali Ahmed aa5635737 at gmail.com
Tue Aug 1 20:05:05 CEST 2017


Hi,
Thank you for your help.

well I used this command

gmx grompp -f em.mdp -c box.gro -p topol.top -o em.tpr
gmx mdrun -v -deffnm em

and I got all the warnings. Here is my em.mdp
-------------------------------------------------------------------------------------

integrator         = steep

emtol               = 10.0

emstep          = 0.001

nsteps              = 50000

energygrps       = system

; Parameters describing how to find the neighbors of each atom and how to
calculate the interactions

nstlist                   = 1

cutoff-scheme       = group

ns_type                            = grid

coulombtype        = PME

rcoulomb             = 1.0

rvdw                    = 1.0

pbc                      = xyz

On Tue, Aug 1, 2017 at 11:07 AM, Mark Abraham <mark.j.abraham at gmail.com>
wrote:

> Hi,
>
> No, only mdrun issues LINCS warnings. grompp issues different warnings, and
> I would like you to check whether you had any from grompp that you may not
> have considered. :-)
>
> Mark
>
> On Tue, Aug 1, 2017 at 5:04 PM Ali Ahmed <aa5635737 at gmail.com> wrote:
>
> > Dear Mark
> > Yes, all the warnings are from grompp.
> > I have no idea where is the problem in the structure or the topology
> > Thank you
> >
> > On Mon, Jul 31, 2017 at 2:34 PM, Mark Abraham <mark.j.abraham at gmail.com>
> > wrote:
> >
> > > Hi,
> > >
> > > Did you get any warnings from grompp?
> > >
> > > Mark
> > >
> > > On Mon, Jul 31, 2017 at 5:48 PM Ali Ahmed <aa5635737 at gmail.com> wrote:
> > >
> > > > Hello GROMACS users,
> > > >
> > > > I'm doing MD for nitrogen, and for better electrostatic interactions
> I
> > > need
> > > > to use massless and charged virtual site. I did that but when I try
> to
> > do
> > > > energy minimization gives me LINCS warning and crush. I don't know
> > where
> > > is
> > > > the error I tried a lot but could not find a solution.
> > > > Anyone has an idea where is my error
> > > >
> > > > Here is the topology file (hand written)
> > > >
> > > > ------------------
> > > >
> > > > [ defaults ]
> > > >
> > > > 1 3 yes 0.5 0.5
> > > >
> > > > ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> > > ;;;;;;;;;;;;;
> > > >
> > > > [ atomtypes ]
> > > >
> > > > ; name  bond_type    mass    charge   ptype          sigma
> epsilon
> > > >
> > > >   OP   OP            0.000   0.000    A              0.330
> 0.3062
> > ;
> > > > nitrogen
> > > >
> > > >   M      M              0.000   0.000    V              0.000
> > 0.000
> > > ;
> > > > virtual site
> > > >
> > > >
> > > > ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> > > ;;;;;;;;;;;;;;;;
> > > >
> > > > [ moleculetype ]
> > > >
> > > > ; name  nrexcl
> > > >
> > > > N2     2
> > > >
> > > >
> > > >
> > > > [ atoms ]
> > > >
> > > > ;   nr       type    resnr residue  atom   cgnr   charge     mass
> > > >
> > > >      1     OP      1    N2     N1      1    -0.482          14.0067
> > > >
> > > >      2     M         1    N2     M1      1     0.964         0.000
> > > >
> > > >      3     OP       1    N2     N2      1    -0.482         14.0067
> > > >
> > > >
> > > >
> > > > [ constraints ]
> > > >
> > > > ; the N-N is fixed
> > > >
> > > >     1   3   1   0.11
> > > >
> > > >
> > > >
> > > > [ virtual_sites2 ]
> > > >
> > > > ; site  ai  aj  funct   a
> > > >
> > > >      2   1   3      1   0.5000  ; right in the mid
> > > >
> > > >
> > > >
> > > > ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> > > >
> > > > [ system ]
> > > >
> > > > N2 in vacuo
> > > >
> > > >
> > > >
> > > > [ molecules ]
> > > >
> > > > N2     1500
> > > >
> > > > ------------------------------------------------------------
> > > > --------------------------------------
> > > >
> > > > Here is the structure (N2.pdb)
> > > >
> > > > -----------
> > > >
> > > > TITLE     N2 with dummy masses
> > > >
> > > > REMARK    THIS IS A SIMULATION BOX
> > > >
> > > > MODEL        1
> > > >
> > > > COMPND    UNNAMED
> > > >
> > > > AUTHOR    GENERATED BY OPEN BABEL 2.3.2
> > > >
> > > > CRYST1   50.000   50.000   50.000  90.00  90.00  90.00 P 1         1
> > > >
> > > > ATOM      1  N1  N2      1       0.000   0.000   0.000  1.00
> > > > 0.00           N
> > > >
> > > > ATOM      2  M1  N2      1       0.55000   0.000   0.000  1.00
> > > > 0.00          Xx
> > > >
> > > > ATOM      3  N2  N2      1       1.100   0.000   0.000  1.00
> > > > 0.00           N
> > > >
> > > > CONECT    1    3
> > > >
> > > > CONECT    3    1
> > > >
> > > > MASTER        0    0    0    0    0    0    0    0    3    0    3
> 0
> > > >
> > > > END0
> > > >
> > > > ------------------------------------------------------------
> > > > ---------------------------------
> > > > Thank you
> > > > --
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