Study of lattice thermal conductivity of PbS

The phonon dispersions and phonon density of states (DOS) of cubic PbS are obtained, based on density functional perturbation theory (DFPT) and the norm-conserving pseudo-potential method. The heat capacity of PbS is calculated then. The anharmonic single-mode relaxation-time is investigated by applying the Fermi's golden rule. Considering two kinds of phonon scattering mechanisms, the lattice thermal conductivity of PbS is obtained. When the temperature rises to about 10 K, the thermal conductivity reaches the maximum. When the temperature is higher than 300 K, the thermal conductivity tends to be stable.