[gmx-users] autocorrelation function

[faride badalkhani]

Dear Gromacs users,

I calculate autocorrelation function of Rg using the following command:

gmx analyze -f gyrate.xvg -o ac

now I have two questions:

1) when I obtain Rg there are 3 columns in the file including Rg, Rg x, Rg
y, and Rg z, respectively. Is this trend correct for the acf file, too. I
mean do we have ac, ac x, ac y, and ac z, respectively?

2) when I get the ac file for one on the structures the first and the
second set of data have "zero" value for all the time steps, but the other
sets have reasonable values. What does that mean?

Regards,
Farideh