The electron localization function ELF, which is crafted to reveal chemical
bonds and their properties, has been generalized to the time-dependent regime.
This allows the time-resolved visualization of the formation, modulation and
breaking of bonds and gives thus insight into the dynamics of excited
electrons. This has been illustrated by the pi–pi* transition of ethyne
induced by a laser field, and by the destruction of bonds and the formation of
lone-pairs in a scattering process of a proton with ethene. In the second
part, an optimal control algorithm is used to determine an optimized laser
pulse of a HOMO–LUMO transition of the diatomic molecule lithium fluoride.