[gmx-developers] REMD and network.c

alberto alberto at maxwell.ucsf.edu
Fri Mar 19 16:05:28 CET 2010

Hi Developers,
I'm trying to run REMD with current git versions and I'm finding some problems.
It seems that the replica parameters for seed and temperature (repl_ex.c) loose
their real values when passing through gmx_sumi_sim   (seed) and gmx_sum_sim
(Temperatures) in network.c
This produces errors when trying to interchange replicas (each replica runs
normal MD at correct temperature until the exchange point):

Repl      1     0
Repl  T   0.0 396316835928080384.0
Repl  exchange interval: 1000

Repl  random seed: 0
Repl  below: x=exchange, pr=probability

[sim runs fine until first step in which it has to exchange]

Replica exchange at step 1000 time 2
Repl 1 <-> 0  dE =       -inf

Here is the output for the same input when running with the latest stable
version (4.07)

Repl      0     1
Repl  T 300.0 315.0
Repl  exchange interval: 1000

Repl  random seed: 954549
Repl  below: x=exchange, pr=probability
[and everything runs perfect]

Unfortunately I can't really see how to fix it and have not seen any post on the
thanks for your help,

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