Band Structure of Solid Argon

The orthogonalized plane wave method, in a perturbation approximation recently introduced by Bassani and Celli, is used to compute the lowest lying conduction states in (fcc) solid argon at the symmetry points $\Gamma$, $X$, $L$, and $K$. The $3s$ and $3p$ valence bands are treated by tight-binding theory. The potential used in the computation consists of a sum of effective atomic potentials in which a free-electron-like expression is used for the exchange contribution. The lowest conduction state appears to be $s$-like (${\Gamma }_1$), lying 12.4 ev above the highest valence state (${\Gamma }_{15}$). The results of the computation are compared with present theoretical and experimental knowledge of the electronic structure of the solid rare gases.