0_7632 Bilayer WTe2 is a remarkable two-dimensional metal, since it exhibits a macroscopic out-of-plane electric dipole in spite of the presence of charge carriers that screen the electrostatic forces between ions [1]. Intriguingly, at low temperature the system develops a narrow transport gap, which has many-body origin and was attributed to the permanent condensation of excitons, electron-hole pairs bound by Coulomb attraction [2]. Contrary to other known bilayer excitonic insulators, in which electrons and holes are spatially separated, in WTe2 interlayer tunneling is significant. This might impact the observable features of the putative exciton condensate, giving rise to a coherent contribution to the electric dipole, due to the interband electric polarization of excitons.In this work we investigate bilayer WTe2 from first principles, focusing on excitons by solving the Bethe-Salpeter equation of motion. The ultimate goal is to assess the instability of the system against exciton condensation, as well as to predict its possible experimental fingerprint. [1] Fei et al., Ferroelectric switching of a two-dimensional metal. Nature 560, 336-
339 (2018).[2] Sun et al., Evidence for equilibrium exciton condensation in monolayer WTe 2 .
Nature Physics, 18, 94–99, (2022).