As for the electrical properties, our predictions of the lattice thermal conductivity are generally in good agreement with experimental measurements and other calculations. Our predicted 300 K κ latt = 2.18 W m -1 K -1 for Pnma GeSe compares favourably to the measured values of 1.8 -2.9 W m -1 K -1 , The axial components are also similar to reported values of 2.3, 0.64 -1.11 and 4.8 W m -1 K -1 along the a, b and c directions. At a higher T = 700 K, our predicted average value of 0.92 W m -1 K -1 is also comparable to the 0.85 W m -1 K -1 reported in Ref. . We note that our calculated κ latt of Pnma GeS and GeSe are substantially larger than the minimum values of 0.52 and 0.39 W m -1 K -1 predicted by the approximate model in Ref. , but the poor agreement with previous experimental and theoretical studies on GeSe suggest this model may not make realistic predictions. On the other hand, the predicted κ latt = 0.98 W m -1 K -1 along the b direction of Pnma GeS at T = 700 K predicted in Ref. is much larger than our predicted 0.56 W m -1 K -1 , which we attribute to the use of PBE and a smaller 64-atom supercell used to compute the force constants.