[gmx-users] Question about nsttcouple

[Quyen Vu Van]

nsttcouple=10 means that nsstcouple*dt(2fs, I guess)=0.02 and your
tau-t=0.1 (5 fold)
when nsttcouple=20, nsstcouple*dt=0.04 so your tau-t is only 2.5 fold. I
think so

On Wed, Nov 7, 2018 at 3:43 PM minky son <minky0710 at gmail.com> wrote:

> Dear gmx users,
>
>
> In gromacs manual,
>
> “nsttcouple: The default value of -1 sets nsttcouple equal to nstlist,
> unless nstlist <=0, then a value of 10 is used.”
>
>
>
> When I did grompp with the following mdp options,
>
> nstlist = 20
>
> tcoupl = berendsen
>
> nsttcouple = -1
>
> tau-t = 0.1
>
>
>
> I got a warning message.
>
> WARNING 1 [file pr_nvt.mdp]:
>
>   "For proper integration of the Berendsen thermostat, tau-t (0.1) should
> be at least 5 times larger than nsttcouple*dt (0.04)"
>
>
>
> I think this means that nsttcouple is applied to 20, not 10. This doesn't
> match with the one mentioned in the manual. why?
>
>
>
>
>
> When I also tried nstlist=10, grompp didn’t show any warning.
>
> But the value of nstlist was automatically changed to 40 in mdrun.
>
> Is nsttcouple applied to 10 in this case?
>
>
>
> Please give me an advice.
>
> Thank you.
> --
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