Fig. 6. Dielectric response matrices computed from first principles for monolayer TaS₂ in a supercell arrangement with a cell length of L = 100 Å along the direction normal to the layer and with numerical broadening of 0.1 meV.

a Real and (b) imaginary parts of the G = G’ = 0 components of the inverse dielectric matrices of such dilutely stacked monolayers for three different in-plane wavevectors q, where G is a reciprocal lattice vector of the quasi-2D crystal. The imaginary part plotted in panel (b) is proportional to the loss function, the sharp peaks of which are associated with plasmon excitations. c Real part of the macroscopic dielectric matrix, the zeros of which are associated with plasmon collective excitations. While the absolute values of dielectric matrices depend on the stacking spacing and broadening parameter used in our supercell calculations, the poles in panels (a) and (b), as well as the zeros in panel (c), are not sensitive to such details.