Phonon spectra and phonon linewidths of the (d) monolayer, (e) bilayer, and (f) T-bilayer. The magnitude of the phonon linewidth is indicated by the size of the red error bar, and the magnitude for the bilayer is plotted with ten times the real values. The large phonon linewidths mainly focus on the Γ point in the high-frequency region (350∼400 cm⁻¹).