Simulating valence and core excitons in solids within velocity-gauge real-time TDDFT.

The application of real-time TDDFT (RT-TDDFT) to describe light-matter interactions in periodic solid-state systems has thus far been largely limited to situations where excitonic effects are not crucial primarily due to the inability of semi-local exchange-correlation (XC) functionals to describe exciton binding. In particular the simulation within TDDFT of accurate core-excitation spectra that are often strongly modulated by solid-state excitonic effects has been hindered. In this work, a recent atomic orbital basis implementation [1] of real-time TDDFT that exploits range-separated hybrid XC functionals within the generalized Kohn-Sham formulation [2] to simultaneously describe both valence and core excitonic effects in solids is presented. Optical properties and excitons in a number of representative solid-state systems are discussed from a time-domain perspective. Applications of the methodology to time-resolved core and valence spectroscopies are illustrated.

[1] C. D. Pemmaraju arXiv:1810.00473
[2] R. Baer et al, Eur. phys. j. b 91 (7) (2018) 170.