Hello, I run a 5ns simulation for a single glucose molecule in gas phase. I tried to plot radial distribution function for O---H intramolecular interactions using following command. g_rdf -f 6.trr -s 6.tpr -n index -o In rdf.xvg file there is no data. Can you tell what could be the reason. I am using Gromacs 4.0.7 version. Thanks Nilesh