Time-dependent dielectrically screened hybrid TDDFT for ultrafast excitonics

Dielectrically screened hybrid TDDFT has been shown to provide an accurate and efficient description of excitonic signatures in the optical absorption spectra of periodic solids. Here, we extend the formalism into the real-time domain to describe ultrafast linear and nonlinear excitation processes. We define the time-dependent dielectric function and use it to construct a hybrid functional combining screened time-dependent Hartree-Fock with local exchange-correlation. With this hybrid TDDFT approach we then simulate exciton formation in a two-dimensional model solid following short-pulse excitations of various intensities.