Electronic and dielectric characteristics of sI, sH hydrates and Ih, III ices: ab initio research results

By ab initio modeling method for the lattices of ices Ih, III, and lattices of hydrates sI, sH the densities of electronic states were obtained, electronic εel and ionic εion contributions to the static dielectric tensor were calculated. Ices Ih, III and hydrate sH show a dedicated axis of the dielectric tensor εel, and hydrate sI demonstrates isotropy of εel. The inclusion of Xe and CH4 in the sI hydrate stabilizes the lattice and increases the values of the dielectric tensors εel and εion, due to increased polarizability. The study of the dielectric functions ε'(ω) and ε"(ω) shows the presence of active absorption at energies of 5 ÷ 20 eV, and an optical gap EOG ≈ 5 eV.