All-electron local-density theory of covalently bonded material adsorbed on metallic substrate:p(1×1) Si monolayer on W(001)

Results of self-consistent all-electron local-density-functional total-energy calculations of a Si monolayer on the W(001) surface employing the full-potential linearized augmented plane-wave method are presented. For an ordered p(1×1) overlayer of Si on the W(001) substrate we find a Si-W bond length of 2.59 Å, which is very close to that of bulk ${\mathrm{WSi}}_2$ (2.62 Å). Surprisingly, compared to that of the clean W(001) the work function is not changed appreciably as a result of the covalent bonding. The strong covalent bonding between the Si and W atoms is found to suppress the localized surface states of the clean W(001) surface. Si-W interface bonding states are found at the symmetry points Γ¯ and M¯ in the surface Brillouin zone with binding energies of -10.5 and -7.8 eV, respectively.