Alkali metal adsorption on graphite: Calculation of a work function variation in the Anderson-Newns-Muscat model

Within the scope of the Anderson-Newns model of adsorption the Na, K, and Cs submonolayer films on graphite are considered. The adatoms dipole-dipole repulsion is taken into account with the use of the Muscat approach. The calculated work function variations are in a reasonable agreement with the experimental data. We have found that the charges of K, Na, and Cs adatoms are Z₀ = 0.22, 0.38, and 0.41 for the zero coverage limit and Z_ML = 0.09, 0.15, and 0.16 for the monolayer coverage correspondingly. The crude estimations of the single adatom binding energies got E_b = 0.76, 0.67, and 0.37 eV for Na, K, and Cs accordingly.