[gmx-users] editing velocities in tprs

[Alex Robertson]

how do you grompp velocities?  Would I put have to extract them into a gro 
and then grompp that?

I don't think that which time step I take the velocities from matters 
because it's only a femtosecond difference and I'm not trying to test 
reversibility.

Thanks
Alex Robertson
----- Original Message ----- 
From: "Berk Hess" <gmx3 at hotmail.com>
To: <gmx-users at gromacs.org>
Sent: Wednesday, July 06, 2005 12:54 AM
Subject: RE: [gmx-users] editing velocities in tprs


>
>
>>From: "Alex Robertson" <alexrson at stanford.edu>
>>Reply-To: Discussion list for GROMACS users <gmx-users at gromacs.org>
>>To: "Discussion list for GROMACS users" <gmx-users at gromacs.org>
>>Subject: [gmx-users] editing velocities in tprs
>>Date: Tue, 5 Jul 2005 15:00:46 -0700
>>
>>Hi
>>    I am trying to take some tprs that I have created and create new one's 
>> with all the velocities inverted.  Does anyone know how to edit the 
>> information in tprs?  Or how to take the output from gmsdump and turn 
>> that into a run input file?
>
> I guess the easiest thing is editing grompp to reverse the velocities.
>
> But why do you want to do this?
> If it is for reversibility test of the leap-frog integrator
> you also have to take the velocities of the next step,
> as the velocitities are stored at half steps.
>
> Berk.
>
>
> _______________________________________________
> gmx-users mailing list
> gmx-users at gromacs.org
> http://www.gromacs.org/mailman/listinfo/gmx-users
> Please don't post (un)subscribe requests to the list. Use the www 
> interface or send it to gmx-users-request at gromacs.org.