Re: [AMBER] calculating MSD by correcting the center-of-mass-motion

From: Vijay Manickam Achari <vjrajamany.yahoo.com>
Date: Mon, 13 Jan 2014 08:59:33 +0000 (GMT)

Dear Hannes,

Thanks for the info.

Regards
 

Vijay Manickam Achari
(Phd Student c/o Prof Rauzah Hashim)
Chemistry Department,
University of Malaya,
Malaysia
vjramana.gmail.com



On Friday, 10 January 2014, 20:02, Hannes Loeffler <Hannes.Loeffler.stfc.ac.uk> wrote:
 
On Fri, 10 Jan 2014 11:27:51 +0000
Vijay Manickam Achari <vjrajamany.yahoo.com> wrote:

> Dear Sir,
>
> I have treid to run stfcdiffusion comamnd from cpptraj.
>
> the command I used is as blow.
>
> stfcdiffusion mask :BCM.1 out diffusion_in_XY_plane.dat time 5 avout
> distance com xy
> What I wanto calculate is the diffusion of atom number 1 from residue
> BCM.
>
> I get the output file with 5 columns with the first one representing
> time.
>
> But I find difficulty in finding the meaning of those columns wiht
> the firstone to the time evolution.
>
> Could you explain briefly what the coluns aer reperesenting. Further
> I get another file called "distance" with only one line data in it. 
>
> I want the diffusion along  xy plane.

The output file should contain a header explaining what is in each
column (maybe Dan forgot to include that).  Column 2-4 is for x, y, z
and column 5 is the data for your chosen direction i.e. xy (this column
is actually redundant as you could easily compute this from cols 2 and 3
obviously).

You get a file named "distance" because you have asked for it with
avout (the next argument to the right is a filename).

"com" requests for the center-of-mass motion of the atoms in "mask"
which seems to be useless here since you obviously want to compute the
MSD for a single atom.  I would also think that the MSD for a single
atom won't be well determined statistically.


Cheers,
Hannes.
-- 
Scanned by iCritical.
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Received on Mon Jan 13 2014 - 01:00:02 PST
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