[gmx-users] Questions to pullx.xvg

[Thomas Schlesier]

Hi all,
what are the meanings of the columns X and dX? From the manual i think
the first column X should be the position of the pull-group. But in my
case it is the position of the reference group, so i'm a little bit
troubled. And what is dX? For me it looks that this is the vector from
the reference-group to the pull-group. And then the forces in pullf.xvg
were calculated with:
F(t)= k*[S - (RP(t)-RP(0))]
Where F is the force, S the vector from the reference-group to the
spring (= pull_init + t * pull_rate * pull_vec) and RP the vector from
the reference-group to the pull-group and t the time.
(I used the umbrella pulling, with pull-geometry = position)
Am i right?

Greetings Thomas