I used gmx trjconv -b 100000 -e 150000 -f wild_nopbc.trr -s NPT_wild_0_eq.tpr -pbc mol -o wild_100ns_150ns.trr to get equilibrated trajectory over 50 ns from 100 ns to 150 ns. Is there any way to get the exact coordinates of my system at 100 ns (The starting point of my equilibrated trajectory).