Energy transfer from intense laser pulse to dielectrics in time-dependent density functional theory

Energy transfer processes from a high-intensity ultrashort laser pulse to electrons in simple dielectrics, silicon, diamond, and $\alpha$-quartz are theoretically investigated by first-principles calculations based on time-dependent density functional theory (TDDFT). Dependences on frequency as well as intensity of the laser pulse are examined in detail, making a comparison with the Keldysh theory. Although the Keldysh theory reliably reproduces the main features of the TDDFT calculation, we find some deviations between results by the two theories. The origin of the differences is examined in detail.