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

[Anton Feenstra]

Alan Wilter Sousa da Silva wrote:
> 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.

OK, that puts things in perspective, thanks.
Indeed, MD is chaotic, but deterministic (these are not exclusive!).


-- 
Groetjes,

Anton
  _____________ _______________________________________________________
|             |                                                       |
|  _   _  ___,| K. Anton Feenstra                                     |
| / \ / \'| | | Dept. of Pharmacochem. - Vrije Universiteit Amsterdam |
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