[gmx-developers] re: Energy and Foreign Lambdas and Hamiltonian Replica

[David Mobley]

Dear Berk,

> I have implemented replica exchange for the free-energy lambda in the
> CVS head branch,
> based on linear extrapolation of dV/dlambda (not foreign lambda energies).
> I haven't tested it though.
> Please tell me if it works or not.

I'm fairly concerned about exchanging based on linear extrapolation of
dV/dlambda. In my experience, dV/dlambda can be pretty nonlinear,
especially in the case when soft core potentials are used -- even if
lambda spacings are pretty close. I'm thinking the risks of doing
things this way may outweigh the benefits, and that it would probably
be better to hold off until foreign lambda energies are in that branch
also.

Thanks,
David


> Berk.
>
> servaas michielssens wrote:
>
> > Thanks, for your fast reply and for the code.
> > I had a look in the code but I can't find the swapping probability for
> > hamiltonian replica exchange. I expected this in repl_ex.c but I can't
> > find anything like it. I could not locate another function in md.c or
> > mdrun.c to do the hamiltonion replica exchange. Could you help me al
> > little further here were to look?
> >
> >
> >
> > thanks!
> >
> > servaas
>
>
>
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