Real-Time Exciton Dynamics with Time-Dependent Density-Functional Theory

Linear-response time-dependent density-functional theory (TDDFT) can describe excitonic features in the optical spectra of insulators and semiconductors, using exchange-correlation (xc) kernels behaving as $-1/k^{2}$ to leading order. We show how excitons be modeled real-time TDDFT, an xc vector potential constructed from approximate, long-range corrected kernels. demonstrate for various materials that this approach is consistent with frequency-dependent linear response, gives access femtosecond exciton dynamics following short-pulse excitations, extended some caution into nonlinear regime.