“…In addition, the zero-point energy should be included in the phonon occupation number when the temperature is above onethird of T D . [249] At low temperature, other methods, such as Monte Carlo simulations [213,[250][251][252][253][254][255][256] and ab initio calculations [257][258][259] mainly based on the discussion in Section 3.2.1, are more applicable to obtain κ and have been largely applied in recent literature on PnCs and MMs. Other methods, such as the Allen-Feldman theory for disordered harmonic solids [260] and atomistic Green's function method, [261] have also been widely used to study phonon transport, however, with constraints, including the negligence of anharmonicity, which requires further adaptations in their applications.…”