FW: [gmx-users] Re: Simulations backward in time

[Berk Hess]

From: gmx3 at hotmail.com
To: vvchaban at gmail.com
Subject: RE: [gmx-users] Re: Simulations backward in time
Date: Thu, 21 Aug 2008 16:11:56 +0200







Surely inverting the velocities changes the direction of the system evolution.
The state of the system is given by x and v. The evolution is determined
by the state and the potential. The only time direction information is in the sign of v.
Note that due to numerical issues you will never get back the inverse of
an original trajectory when inverting the velocities.

Berk


> Date: Thu, 21 Aug 2008 16:53:07 +0300
> From: chaban at univer.kharkov.ua
> To: jhub at gwdg.de; gmx-users at gromacs.org
> Subject: Re: [gmx-users] Re: Simulations backward in time
> CC: 
> 
> In conf.gro? It will change only the first steps but will not change
> the direction of the system evolution.
> 
> As I understand, the topicstarter wanted to perform the simulation
> "backwards"...
> 
> Vitaly
> 
> 2008/8/21 Jochen Hub <jhub at gwdg.de>:
> > Vitaly Chaban wrote:
> >>>
> >>>  I wanted to perform some simulations backward and forward in time (for
> >>> transition path sampling ). If I specify a negative value for 'dt' in the
> >>> mdp file, would that work for backward integration of the equations of
> >>> motion ?
> >>>
> >
> > You could also invert the initial velocities. Shouldn't that be the same as
> > using a negative dt ?
> >
> > jochen
> >
> > --
> > ************************************************
> > Dr. Jochen Hub
> > Max Planck Institute for Biophysical Chemistry
> > Computational biomolecular dynamics group
> > Am Fassberg 11
> > D-37077 Goettingen, Germany
> > Email: jhub[at]gwdg.de
> > Tel.: +49 (0)551 201-2312
> > ************************************************
> >
> 
> 
> 
> -- 
> Vitaly V. Chaban
> School of Chemistry
> National University of Kharkiv
> Svoboda sq., 4, Kharkiv 61077, Ukraine
> email: chaban at univer.kharkov.ua
> skype: vvchaban
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