Pullx file

GROMACS version: 2019.5
GROMACS modification: No

I have two peptide chains in a water box and I am running a pulling simulation with the following parameters:

pull                    = yes
pull_ncoords            = 1
pull_ngroups            = 2
pull-coord1-groups      = 1     2
pull-group1-name        = ChainA
pull-group2-name        = ChainE
pull-coord1-type        = umbrella
pull-coord1-geometry    = direction-periodic
pull-coord1-vec         = 1 1 1
pull-coord1-dim         = Y Y Y
pull-nstxout            = 1000
pull-nstfout            = 1000
pull-pbc-ref-prev-step-com = yes
pull_coord1_start       = yes
pull_coord1_rate        = 0.0001
pull_coord1_k           = 1000
pull-print-components   = yes

I am getting the following pullx.xvg file (only shown first few lines):

@ s0 legend "1"
@ s1 legend "1 dX"
@ s2 legend "1 dY"
@ s3 legend "1 dZ"
0.0000  0.572965        0.0275484       1.00457 -0.0397192
2.0000  0.552969        -0.00228377     1.00714 -0.0470847
4.0000  0.568279        0.0204535       1.02422 -0.0603869
6.0000  0.575189        0.0152132       1.0322  -0.0511544

I think the last three columns correspond to the three components of the distance between the two pulling groups (I can confirm this using the tool gmx distance). However, I do not understand to what corresponds the second column.

Many thanks in advance.

Hi,
first column is time, the second column is the distance, 3-5 columns are the components of the distance.
\Alessandra