[gmx-users] (no subject)

[Mark Abraham]

Christian Hedegaard Jensen wrote:
> Hi
> 
> I need to do an MD simulation backwards in time. Is this possible?

Possible, yes - you just negate the forces and pretend that time is 
negative. Useful, no - you will not be able to follow a system forward 
in time and then take it back to the starting point because the system 
representation and the integration algorithm are both finite-precision. 
I'm not sure whether the ensemble formed from negating the forces has 
any physically-meaningful interpretation.

Mark