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

[Ganesh Shahane]

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
> > > --
> > > Gromacs Users mailing list
> > >
> > > * Please search the archive at
> > > http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before
> > > posting!
> > >
> > > * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
> > >
> > > * For (un)subscribe requests visit
> > > https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
> > > send a mail to gmx-users-request at gromacs.org.
> > >
> > --
> > Gromacs Users mailing list
> >
> > * Please search the archive at
> > http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before
> > posting!
> >
> > * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
> >
> > * For (un)subscribe requests visit
> > https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
> > send a mail to gmx-users-request at gromacs.org.
> >
> --
> Gromacs Users mailing list
>
> * Please search the archive at
> http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before
> posting!
>
> * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
>
> * For (un)subscribe requests visit
> https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
> send a mail to gmx-users-request at gromacs.org.
>



-- 
Best Regards,
Ganesh Shahane