Swati, I believe you are confusing yourself by defining a cell for the compound "CrC6" when I think you really mean to define CrC8, and using the wrong number of carbon atoms which trigger the "atoms too close" error. Look closely at your list and delete atoms that are defined in your cell that are equivalent to others by adding/subtracting a translation vector. Since you have repeated atoms, using a visualizer where you can inspect atoms by their index may be helpful. According to your error messages, it seems that atoms 1,2, 5 and 11 have no duplicates, but every other one might be duplicated.
I have deleted repeated atoms and visualized the result, and I have what looks like the correct input structure. Good luck and cheers, *Abraham Hmiel* Katherine Belz Groves Fellow in Nanoscience Xue Group, SUNY College of Nanoscale Science and Engineering http://abehmiel.net/about
