Cohesive Energy and Wave Functions for Rubidium

The cellular method was used to calculate the cohesive energy of rubidium. The potential was obtained from a self-consistent field for ${\mathrm{Rb}}^{+}$ supplemented by an exchange potential. Wave functions were obtained to order $k^2$ in the solid and for the lowest valence electron state in the free atom. A value of 20.7 kcal/mole was obtained for the cohesive energy, including $k^4$ terms in the Fermi energy, but neglecting any polarization effects. The ratio of $\left|{\psi }^2\mathrm{}\right(0\left)\right|$ for an electron on the Fermi surface in the metal to that for an electron in the free atom was computed and found to be in good agreement with results of the Knight shift measurements.