Phonon spectra and lattice thermal conductivity of high-performance thermoelectric SnSe

Tin selenide has record values of the thermoelectric performance, which is largely due to its low lattice thermal conductivity caused by strong lattice anharmonicity. In this work, the effect of temperature and volume on the phonon density of states of the low-temperature SnSe phase with the space group $Pnma$ is analyzed using molecular dynamics simulations. Stabilization of the phase with a $Cmcm$ crystal structure at high temperatures is demonstrated. An anomalously low lattice thermal conductivity of SnSe is obtained from the numerical solution of the linearized Boltzmann transport equation, which is in agreement with experimental data over a wide temperature range.