[gmx-users] Pressure coupling in expanded ensemble simulations

[Michael Shirts]

Yeah, this is an unfortunately place in the code where not all combinations
work - very long story.  Hopefully this will be working better in 2020.

What I would recommend is, if possible, performing the expanded ensemble
simulation at NVT.  Everything should work fine there (paper coming out
hopefully soon comparing a bunch of free energy methods).  Once can always
correct the free energy at lambda=1 from NVT to NPT.  I Can fill in the
details.

You do NOT want to do Berendsen for NPT when running expanded ensemble.
The results will be incorrect (as I have learned by sad experience_

On Wed, May 8, 2019 at 8:14 AM Gregory Man Kai Poon <gpoon at gsu.edu> wrote:

> Hi all:
>
> We are interested to do expanded ensemble simulations (such as simulated
> tempering) on GROMACS.  Extensive fiddling with the settings and
> googling on other people's experience suggests that these simulations
> must use the md-vv integrator, which in turn is compatible with
> Berendsen or MTTK coupling for pressure.  However, MTTK does not work
> with constraints, which are needed for the forcefields.  Berendsen can
> handle constraints but is not recommended for preserving thermodynamic
> ensembles.  Any ideas on how one should proceed?
>
> Many thanks for your thoughts.
>
> Gregory
>
>
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