GROMACS version: 2019.1
GROMACS modification: Yes/No
I used the gmx-clutser to make clutser.sh. And, then I wanted to choose 50 random frames from cluster1. Frames in my trajectory are 20ps apart. Since, the cluster.log mentions time stamp. I divided it by 20 to get the exact frame number and put up my list in frames.ndx, which is further given as an input in trjconv to get *.xtc and *.pdb.
During analysis, I got a *.xvg and I noticed that frames are shifted exactly one place behind. For instance, my *.ndx ask for frame 498 (time = 9660), then, my *.xvg mentions time 9640 (corresponding to frame 497). I do not fully understand why this could be happening.
I am also not sure whether to list it as a problem associated with gmx-trjconv or gmx-cluster.