As in previous work involving nanocluster adsorption onto TMD surfaces , three stable, non-equivalent adsorption sites exist on the TMD monolayer. Atop-X, where Cu adsorbs directly above the chalcogen; Atop-M, where Cu adsorbs above tungsten so that the adsorbed atom is coordinated to three chalcogens; and Hollow, where the adatom is coordinated to three chalcogen atoms but where there is no W underneath the adsorbed species. In addition to this, we define the adsorption site Bridge, where a Cu atom is adsorbed at a bridging site between two chalcogen atoms. These sites are shown in figure . For the sake of brevity, reference to which site a Cu cluster is initially placed will be referred to as X, M, H, or B for Atop-X, Atop-M, Hollow, and Bridge respectively.