First-principles Calculations of Interaction between Intense Optical Field and Materials

Non-equilibrium dynamics induced by the femtosecond laser shot has attracted high attentions in condensed matter community. Interaction between a strong field of light and materials cannot be treated by conventional perturbation theory that assumes both electron wave functions and ionic positions as insensitive to the field. Direct approach for computing real-time propagations of electron wave packet and ionic positions under presence of strong optical field is one of promising solutions. In this review, I present theoretical approaches based on the time-dependent density functional theory and show some examples of ultra-fast dynamics in materials induced by the femtosecond laser shots: exfoliation of graphene layer from graphite and photochemical reaction of molecules encapsulated inside carbon nanotubes.