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

[gozde ergin]

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.
>
>
>
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> 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:
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> > *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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