AMBER Archive (2007)

Subject: Re: AMBER: extracting starting structures from equilibration trajectory

From: Ilyas Yildirim (yildirim_at_pas.rochester.edu)
Date: Thu Jun 07 2007 - 13:14:18 CDT


The .mdcrd files do not store any velocity information. So, when u extract
the restart files from a .mdcrd file using ptraj, they wont have any
velocity information in them. As a result, u need to re-equilibrate each
system. Only .rst files have velocity info. in them.

On Thu, 7 Jun 2007, Nikola Trbovic wrote:

> Dear all,
>
>
>
> I'm trying to use snapshots from an NPT equilibration trajectory as starting
> structures for several NVE production runs. I tried extracting snapshots as
> Amber restart files from the equilibration trajectory as follows:
>
>
>
> ptraj prmtop << EOF
>
> trajin equi.mdcrd 300 1000 100
>
> trajout start restart
>
> EOF
>
>
>
> This produces 8 restart files from the equilibration trajectory, just like I
> want it to. But when I start the production runs with irest=1 and ntx=5, the
> temperature starts out around 190K, although it is clearly equilibrated at
> 300K in the time window of the NPT equilibration trajectory that I specified
> for extracting the starting structures by ptraj. How do I fix this?
>
>
>
> Thanks a lot in advance for any suggestions,
>
> Nikola
>
>

-- 
  Ilyas Yildirim
  ---------------------------------------------------------------
  - Department of Chemistry      -				-
  - University of Rochester      -				-
  - Hutchison Hall, # B10        -				-
  - Rochester, NY 14627-0216     - Ph.:(585) 275 67 66 (Office)	-
  - http://www.pas.rochester.edu/~yildirim/			-
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