Hi alevilla, your suggestion now solves my issue. I would write here so that it would be helpful if someone stuck with same problem.
I had used following gromacs codes in order to get the coordinates of molecule A without pbc or jump:
- gmx trjconv -f nvt.xtc -s nvt.tpr -pbc no jump -o nvt_nojump.xtc -tu ns
- gmx trajectory -f nvt_nojump.xtc -s nvt.tpr -ox position_moleculeA.xvg -seltype mol_com