Actually, I want to calculate well depth for selenium atom and I have only its Vander Vaal radius and covalent radius. I am not getting how to calculate the well depth.
Covalent radius equals to half of the covalent bond length. It looks a quite reasonable value to estimate atomic well in the same material (with covalent bond) if a surface reconstruction can be neglected. I have no idea about Se: if there is a reconstruction for it or no.