[gmx-users] Fwd: NVT to NVE ensemble, energy drifting problem

[gozde ergin]

Hi Ganesh

I tried your suggestion and this time instead of decreasing, potential and
kinetic energy kept increasing!
So still could not get the converged-constant energy for NVE.


On Wed, Nov 4, 2015 at 4:23 PM, Ganesh Shahane <ganesh7shahane at gmail.com>
wrote:

> Hi Gozde,
>
> You could try modifying and introduce some of the parameters as follows
> (keeping the rest same) -
>
> lincs_iter = 2
> rvdw-switch = 1.1
> vdwtype = Cut-off
> vdw-modifier = Force-switch
>
> I recently faced some of the same problems as yours and the above
> parameters worked for me.
>
> On Wed, Nov 4, 2015 at 2:47 PM, gozde ergin <gozdeeergin at gmail.com> wrote:
>
> > Dear Chaban,
> >
> > I decreased the time step and also I run by using double precision
> however
> > energy kept decreasing and did not converge.
> >
> > Does anybody has an opinion how to run NVE simulation in Gromacs without
> > energy drifting?
> >
> > Bests
> >
> >
> > On Tue, Nov 3, 2015 at 7:27 PM, Vitaly V. Chaban <vvchaban at gmail.com>
> > wrote:
> >
> > > Decrease the time-step.
> > >
> > >
> > >
> > >
> > > On Tue, Nov 3, 2015 at 3:00 PM, gozde ergin <gozdeeergin at gmail.com>
> > wrote:
> > >
> > > > ---------- Forwarded message ----------
> > > > From: gozde ergin <gozdeeergin at gmail.com>
> > > > Date: Tue, Nov 3, 2015 at 5:39 PM
> > > > Subject: NVT to NVE ensemble, energy drifting problem
> > > > To: mailing list Gromacs <gromacs.org_gmx-users at maillist.sys.kth.se>
> > > >
> > > >
> > > > Dear Gromacs user,
> > > >
> > > > I did some simulation in NVT ensemble now I need to switch and do
> some
> > > more
> > > > simulations in NVE ensemble.
> > > > What properties do I need to change in .mdp file to get a good energy
> > > > conversion?
> > > > I used the same properties like NVT without temperature coupling but
> my
> > > > potential and kinetic energy drifted a lot.
> > > > What should I do prevent this drifting?
> > > >
> > > > Here is my nvt.mdp:
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > *integrator               = md     dt                       =
> > > > 0.002nsteps                   = 10000000   ; 20 nsnstxout
> > > > = 10000nstvout                  = 10000nstlog                   =
> > > > 10000nstenergy                = 10000continuation         = no
> > > > constraint_algorithm = lincs  constraints          = all-bonds
> > > > lincs_iter           = 1        lincs_order          = 4
> ns_type
> > > > = grid             nstlist     = 5                rlist       =
> > > > 1.2               rcoulomb    = 1.2              rvdw        =
> > > > 1.2              coulombtype     = PME        pme_order       =
> > > > 4             fourierspacing  = 0.16         tcoupl
>  =
> > > > nose-hoovertc-grps                  = Systemtau_t
> =
> > > > 1.0ref_t                    = 300Pcoupl                   = Nopbc
>  =
> > > > xyz                DispCorr    = EnerPres          gen_vel     =
> > > > yes            gen_temp    = 310               gen_seed    =
> > > > -1               nstcomm         = 10comm-mode       =
> > > > Linearcomm-grps       = System *
> > > > For nve, I just make the temperature coupling off and used the same
> > > > properties however as I mentioned my energy could not converged in 20
> > ns.
> > > >
> > > > Thanks in advance
> > > > --
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>
>
> --
> Best Regards,
> Ganesh Shahane
> --
> Gromacs Users mailing list
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