Ab-initio thermal properties of high-pressure silica

We investigate the thermal properties of silica as it undergoes a pressure-driven structural phase transition with first principles calculations. We compute the lattice thermal conductivity of SiO₂ for a wide range of temperatures and pressures by solving the Boltzmann transport equation iteratively. We find that, at low temperatures, silica displays a large peak in the in-plane thermal conductivity and a highly anisotropic behavior close to the phase boundary. We further trace back the origin of this behavior by analyzing the phonon contributions to the conductivity.