Hi Asif,
Thank you for the message. I kept all three layers of Ni and Au fixed. Only allowed one layer closer to molecule relaxed. In the tutorial it says ....
"Next, open the optimization_icon Optimization block to specify that the first and last four atoms in the central region (the atoms in the electrode extensions) should be kept fixed during the relaxation. This is very important – if any of these atoms move you no longer have a periodic structure at the edges of the central cell, which is required for generating and attaching device electrodes later on."
