Abnormal thermal conductivity

[sabofavian829-eng]

Hello everyone, I have a tricky problem. When I calculate the thermal conductivity based on the SCP+BTE model, the calculated thermal conductivity increases with temperature, but the increase is not significant. For example, it goes from 0.50 W/mK at 300K to 0.64 W/mK at 800K. Could you please tell me what the reason is and if there is any solution?

[ttadano]

Do you mean you expected a decreasing trend in $\kappa_L$ with raising temperature but you obtained the opposite?

An increase in $\kappa_L$ with temperature can happen if the effect of temperature renormalization (specifically, hardening of phonon modes) is signigicant compared to the increase in the scattering rate by heating.

[sabofavian829-eng]

Yes, Professor Tadano, just as you said.