Ab InitioCalculation of the Spin Susceptibility for the Alkali Metals Using the Density-Functional Formalism

The new variational-principle, density-functional theory of the spin susceptibility $\chi$ is used to make a priori calculations of $\chi$ for the alkalis. Crystalline effects are calculated by the spherical-cell method and the local spin-density approximation is used for the exchange-correlation functionals. The excellent agreement between the results and recent experiments establishes the validity of this new theory and the correctness of the theoretical values for the exchange-correlation enhancement of $\chi$ for a homogeneous electron gas for ${\mathcal{r}}_s\lesssim 5$.