Electronic and thermophysical properties of gas hydrates: ab initio simulation results

The results of an ab-initio molecular dynamics study of the electronic and thermophysical properties of methane hydrate with a cubic sI structure are presented. Good agreement of the simulation results for heat capacity at constant volume and density with experimental data is found. Based on the analysis of the density of electronic states, the temperature dependences of the electronic properties of methane hydrate, including the Fermi energy level, width and boundaries of the band gap are determined. For the empty framework of the hydrate (water clathrate framework), the electron energy spectra $E(\mathbf k)$ were calculated along the directions M-X, X-$\Gamma$, $\Gamma$-M, and $\Gamma$-R. It was found that the presence of CH$_4$ molecules in an aqueous clathrate leads to an increase in the Fermi energy of the hydrate from 2.4 to 3.0 eV.