I tried to calculate the RMSD using Discovery Studio. I get the error " The order of the atoms has to be the same". How to rectify this error. Is there any other tool to calculate the RMSD value?
You should be try superimpose ligand using small molecule superimpose align method in Discovery Studio; and in Maestro you can also superimpose both ligands and get RMSD values.
Discovery may not be able to give a desired result
If you need RMSD from the docking activity try using MOE for refined RMSD for the docking. The post-calculation data on the DataViewer comes with refined RMSD (rmsd_refine) with other data like docking score (S). Attached herewith is the screenshot from MOE DataViewer showing the rmsd_refine information.
Whenever docking perform with pyrx or autidock vina, it minimises on basis of binding energy that shows the 0.000 RMSD values that included upper bound and lower bound RMSD values.