Band structure of solid HF

Abstract

The molecular tight binding method is used to compute the band structure of the HF crystal in the linear chain approximation and in the three-dimensional case. The energy bands are classified according to the symmetry properties of the crystal with the hydrogens fixed in such positions as to give a nonpolar crystal. The results are correlated to the eigen- states of the isolated molecules and display a relevant dependence of the k vector. The 1 sigma and 2 sigma molecular states are little changed in the crystal while the 3 sigma and pi levels produce wide bands, still separated by a gap of about 2 eV. The top of the valence states is Gamma ₁⁺ and the lowest state for the conduction band is Gamma ₄^- corresponding to a 4 sigma Hartree-Fock virtual state. The inter-chain interaction produces effects comparable to those due to the nearest molecules so that a one-dimensional model does not seem to be accurate in this case.