Higher order anharmonicity and polymorphism in the lattice thermal conductivity of transition metal dichalcogenides

We present a comprehensive {\it ab initio} study of the effect of higher-order anharmonicity and polymorphism on the lattice thermal conductivity, ${\bm κ}$, of single-layer transition metal dichalcogenides. We show that four-phonon processes are responsible for an additional suppression of ${\bm κ}