Hi,<br><br>I am trying to calculate a R space R factor and correlation coefficient<br>for a ligand to find out which conformation best fits the density. I would be grateful for any suggestions on how to do this in the least painful but accurate way. I am sure there must be a little army of programs out there.<br><br>At the moment, I am using Overlapmap with a electron density map (CCP4 format) to calculate the first map and&nbsp; a PDB file and an mtz file with structure factors to calculate the second map. I use the options:<br><br>correlate atom<br>real space R<br><br>The program runs without complaint, but the output looks like a complete mess. First of all, the option 'correlate atom' does not seem to work very well, because it still lists residues. At the same time, it seems to give numbers for individual atoms. I am trying to limit the calculation to the ligand residue, but it lists thousands of atoms starting from the residue number of the ligand. Then there are lots
 of negative CCs and R factors, even in regions that I know are very well defined.<br><br>I am using CCP4 6.0.1, and there seems to be no mention of Overlapmap on the problem page.<br><br>Any suggestions?<br><br>Cheers,<br><br>Rob<br><br>Rob Meijers<br>Synchrotron Soleil<br><p>&#32;