Re: [AMBER-Developers] requirement for an even number of replicas in replica exchange?

From: Carlos Simmerling <>
Date: Wed, 25 Sep 2019 11:41:11 -0400

I think conceptually it isn't hard. An easy way would be to alternate
having the first or last replica not involved in exchanges, leaving an even
number to pair for exchange. Right now the first/last attempt exchange on
alternate attempts, which usually fails, so having one of them do nothing
every other time would be similar. The bookkeeping would need to be updated
for things that assume even numbers, and selection of partners is a little
more complicated, but I think it should work without too much rewriting. It
was always easier to code with even numbers, and an extra replica didn't
seem to cost much so we did it that way.
Others might know of specific issues in the current code that would be
difficult to change...

On Wed, Sep 25, 2019, 10:12 AM David Case <> wrote:

> Does anyone have a feeling of how easy/hard it would be allow an odd
> number of replicas in (Hamiltonian) replica exchange?
> ...thx...dac
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Received on Wed Sep 25 2019 - 09:00:02 PDT
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