The electronic work function of the different faces of tungsten

A semi-empirical theory of the electronic work function of the different faces of tungsten is presented. All the parameters entering the theory, except one, are estimated independently. The one adjustable parameter relates to the isotropic contribution to the work function, and, can, in principle, be determined from a self-consistent calculation of the band-structure of the energy levels in the bulk of the metal. The calculated values for the work function are in reasonably good agreement with available experimental data for practically all of the crystallographic planes with the exception of the (100) plane. For the latter, the calculated value is 0.3 eV above the experimental value. It is suggested that a negative contribution to the surface dipole potential from surface states, that exist on this plane, may be the reason of this discrepancy. (Auth.)