Polarizability, plasmons, and screening in T-MoS2 with tilted Dirac bands

In the presence of an external vertical electric field, it is evident that T -MoS2 exhibits tilted Dirac bands which are valley-spin-polarized. Additionally, this material experiences a topological phase change between a topological insulator and band insulator for a critical value of the electric field. Using linear response theory, we calculate yhe polarization function which is in turn used to obtain the dielectric function. This latter quantity is then used to calculate the plasmon dispersion relation and impurity screening corresponding to tilted Dirac bands in both undoped and doped T -MoS2 and the role played by varying the strength of the vertical electric field, the spin-orbit coupling gap, and band tilting.