Thermal conductivity of crystalline Ge₂Sb₂Te₅: lattice contribution and size effects in the cubic phase quantified by approach-to-equilibrium molecular dynamics

Approach-to-equilibrium molecular dynamics simulations are carried out for the cubic phase of crystalline Ge 2 Sb 2 Te 5 , using interatomic forces derived from a machine learning interatomic potential (MLIP) trained with ab initio calculations. The use of this MLIP potential significantly reduces the computational burden, allowing for the study of systems over 70 nm in length. Above 20 nm, the thermal conductivity of the lattice plateaus at <?CDATA 0.37 ± 0.01?> 0.37 ± 0.01 W K −1 m −1 in agreement with measurements reported in the literature. However, below 20 nm, size effects lead to a reduction in thermal conductivity which is systematically calculated.