REAL-TIME APPROACH TO TIME-DEPENDENT DENSITY-FUNCTIONAL THEORY IN THE LINEAR AND NONLINEAR REGIME

The linear and nonlinear response of Si 4 and Na 4 to an external perturbation is investigated in the framework of time-dependent density-functional theory. The time-dependent Kohn–Sham equations, which are the central equations in this approach, are solved in real space and real time. A parallelized implementation to solve these nonlinear, one-particle Schrödinger equations is presented. In contrast to Na 4, Si 4 shows high-harmonic generation far beyond the cut-off predicted by the quasiclassical model and predictions for extended systems.