Light-matter interaction from density functional theory with application to attosecond electron dynamics

We present a methodology to address light-matter interaction with focus on attosecond electron dynamics in 2D materials starting from density functional theory calculations. We combine an accurate DFT-based evaluation of optical matrix elements and Berry connections with the time-resolved Schrödinger equation including several laser pulses, both at the infrared and the x-ray regimes. In the end, carrier dynamics and light absorption can be obtained and readily compared with available experiments without the aid of any phenomenological parameters. Our methodology is particularly suited for DFT calculations based on Gaussian basis sets as those used in codes such as GAUSSIAN or CRYSTAL as a post-selfconsistent procedure. The use of Gaussian basis sets saves computational effort, as all coordinate space integrations become analytical. Our procedure also entails a proper quantification of several approximations for optical matrix elements widely used in the literature and its effect in reproducing experimental curves.