Vertical manipulation is a process of transferring an atom from substrate to STM tip, repositioning the STM tip and transferring the atom back on a desired position. Transferring an atom from substrate to STM tip is done by placing the tip above the atom in a constant current mode, turning off the feedback loop and applying high bias for a few seconds. In some cases it is also required to slowly approach the tip while applying high bias. Sudden spikes or drops in current during this process correspond to either transfer or to the atom being pushed away from the given spot. As such, there is always some level of randomness in this process. Transferring an atom from STM tip to substrate is done the same way but by applying opposite bias.