Nuclear quantum effects in thermal conductivity from centroid molecular dynamics

Understand

We show that the centroid molecular dynamics (CMD) method provides a realistic way to calculate the thermal diffusivity $a=\lambda/\rho c_{\rm V}$ of a quantum mechanical liquid such as para-hydrogen.

• Once $a$ has been calculated, the thermal conductivity can be obtained from $\lambda=\rho c_{\rm V}a$, where $\rho$ is the density of the liquid and $c_{\rm V}$ is the constant-volume heat capacity.
• The use of this formula requires an accurate quantum mechanical heat capacity $c_{\rm V}$, which can be obtained from a path integral molecular dynamics simulation.
• The thermal diffusivity can be calculated either from the decay of the equilibrium density fluctuations in the liquid or by using the Green-Kubo relation to calculate the CMD approximation to $\lambda$ and then dividing this by the corresponding approximation to $\rho c_{\rm V}$.