On the Dynamics of Fast and Ultrafast Irradiation in Clusters and Molecules

We analyze theoretically several dynamical scenarios of irradiation in molecules and clusters. We focus on fast and Ultrafast (UF) processes as attained in various laser setups. We consider both simple laser pulses and pump-and-probe combinations. We explore various such combinations with different frequencies and durations. The basic theory is Time-Dependent Density-Functional Theory (TDDFT) used at the simplest Local Density Approximation (LDA) level together with a simple and robust self-interaction correction. The TDLDA can be complemented by a Relaxation Time Ansatz which accounts for incoherent correlations beyond effective mean field. We explore fast and ultrafast processes starting in the femtosecond range. We next consider several pump-and-probe setups mixing IR and XUV pulses, the latter one possibly delivered within an atto train. We finally explore UF irradiation in the XUV domain leading to creation of deep lying vacancies. Such setups lead to an unexpected response which is analyzed.