Hi again,

I just found the solution to the problem. Using trjconv to specify the timestep 
seems to have helped. Thanks again for the help.

Regards,
Kei

From: gmx-users-boun...@gromacs.org [mailto:gmx-users-boun...@gromacs.org] On 
Behalf Of Kei Sit
Sent: Tuesday, 15 November 2011 9:20 AM
To: Discussion list for GROMACS users
Subject: RE: [gmx-users] Time unit issue with g_anaeig

Hi Mark,

I ran gmxcheck and it returned the following output:

Checking file 1-21.trr
trn version: GMX_trn_file (single precision)
Reading frame       0 time    0.000
# Atoms  7764
Reading frame   49000 time 4900.000


Item        #frames Timestep (ps)
Step         49984    0.1
Time         49984    0.1
Lambda       49984    0.1
Coords       49984    0.1
Velocities       0
Forces           0
Box          49984    0.1

I understand now why the time is 10 times smaller in my analysis, but this now 
raises another question as to why it is 0.1ps per frame. Would it have 
something to do with the converting from a DCD format to a TRR format? I just 
checked the configuration file for my MD run and I can still see that I'm 
running the simulation of 2fs timesteps and saving output every 500 steps which 
should equate to 1ps. Once again, thank you for your time in helping.

Regards,
Kei

From: gmx-users-boun...@gromacs.org [mailto:gmx-users-boun...@gromacs.org] On 
Behalf Of Mark Abraham
Sent: Monday, 14 November 2011 6:47 PM
To: Discussion list for GROMACS users
Subject: Re: [gmx-users] Time unit issue with g_anaeig

On 14/11/2011 5:46 PM, Kei Sit wrote:
Hi all,

I'm new to gromacs so I hope I haven't done something wrong that is extremely 
simple. I have recently been using gromacs to analyse an MD trajectory using 
g_covar and g_anaeig. I have output saved to the trajectory every ps and I 
currently have a trajectory with 49000 frames (49ns).

I initiate g_anaeig with this command:

g_anaeig -v eigenvec.trr  -f 1-21.trr -s protein.pdb -eig eigenval.xvg -proj 
projection.xvg -xvgr -first 1 -last 8

While this is being executed I see this:

Reading frame 1000 time 100.00

which continues increasing as more frames are read.

When I go to visualise projection.xvg, the time scale is in ps (natural as the 
default value is in ps) but it only shows 4900ps and not 49000ps.

My issue is  this, why is the time constantly 10 times smaller than the number 
of frames that are being read? Am I not entering something correctly which 
fixes this?


What does gmxcheck have to say about your trajectory files?

Mark
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