Antw: Re: Antw: [gmx-users] tpbconv for following runs

[Alan Wilter Sousa da Silva]

Hi Anton!


On Tue, 11 Mar 2003, Anton Feenstra wrote:

> However, IMHO, it *really* *doesn't* *matter*! MD is a chaotic process,
> and any small change (hardware, code, compiler, T-coupling, precision)
> will amplify itself in time. If the change is small enough not to be an
> actuall error in its own right, you should be able to live with it.
> So, perhaps to motivate my finding a quick solution, could someone
> explain why in certain cases it might be so important to reproduce the
> exact same run? (This is not an attempt at being cynical ;-)

If you take system with no coupling at all, do a dynamic (using any MD
program) and at the end you invert velocities, redoing the dynamic you
should expect to get the initial atoms positions (but you got
displaciments).  It is just a test we do here to see how far you could go
in a simulation observing the error due to the MD integration. BTW, in
such a way of system I believe it is totally deterministic.  It is just
for curiosity.

Cheers!

-----------------------
Alan Wilter S. da Silva
-----------------------
 Laboratório de Física Biológica
  Instituto de Biofísica Carlos Chagas Filho
   Universidade do Brasil/UFRJ
    Rio de Janeiro, Brasil