Photoexcitation in Solids: First-Principles Quantum Simulations by Real-Time TDDFT

An efficient and state-of-the-art real-time time-dependent density functional theory (rt-TDDFT) method is presented, as implemented in the time-dependent ab initio package (TDAP), which aims at performing accurate simulations of the interaction between laser fields and solid-state materials. The combination of length-gauge and velocity-gauge electromagnetic field has extended the diversity of materials under consideration, ranging from low dimensional systems to periodic solids. Meanwhile, by employing a local basis presentation, systems of a large size are simulated for long electronic propagation time, with moderate computational cost while maintaining a relatively high accuracy. Non-perturbative phenomena in materials under a strong laser field and linear responses in a weak field can be simulated, either in the presence of ionic motions or not. Several quintessential works are - introduced as examples for applications of this approach, including photoabsorption properties of armchair graphene nanoribbon, hole-transfe r ultrafast dynamics between MoS2/WS2 interlayer heterojunction, laser-induced nonthermal melting of silicon, and high harmonic generation in monolayer MoS2 . The method demonstrates great potential for studying ultrafast electron-nuclear dynamics and nonequilibrium phenomena in a wide range of quantum systems.