[gmx-developers] Energy and Foreign Lambdas and Hamiltonian Replica Exchange

[David van der Spoel]

Matt Wyczalkowski wrote:
> Hi,
> 
> I'm investigating the feasibility of implementing Hamiltonian Replica 
> Exchange in Gromacs, so that swaps exchange lambda values (rather than 
> temperatures).  To do this, it is necessary to know energies for a given 
> configuration at other lambda values.  This is an issue which was 
> discussed a number of months ago in the context of the Bennett 
> Acceptance Ratio.
> 
> Before delving in too far into the code, I wanted to get a feel for the 
> current state of development with respect to energy evaluations at 
> different lambdas, as well as whether Hamiltonian Replica Exchange has 
> been considered and/or implemented.  How significant an undertaking 
> would a generalization of Replica Exchange to allow for lambda swaps be?
> 
> Thanks for your time --
> 
> Matt
> 
I'd say a couple of weeks to get it right. You can learn quite a bit 
from the current REMD implementation, but you'd need extra energy 
evaluations. Check the wiki, to see if this is there already, something 
similar is, anyway.

-- 
David van der Spoel, Ph.D.
Molec. Biophys. group, Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205. Fax: +4618511755.
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://folding.bmc.uu.se