<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt">Dear All,<br><br>I want to calculate rdf for carbon-oxygen, carbon-hydrogen and carbon-water using g_rdf but how can I generate an .ndx file that are suitable for these systems ? I searched mailing list and read manual but couldn't generate .ndx file using make_ndx tool. However, I tried to see the make_ndx examples in gromacs wiki page but couldn't reach the wiki page. Could you please help me about generating .ndx file ? <br><br>Carbon in group 1<br>hydrogen in group 2<br>oxygen in group 2<br>group 2 is water<br><br>I will be gratefull for your helps. <br><br>All the best.</div></body></html>