Properties of Molecules in Excited States

Quantum chemical calculations for organic molecules in excited states are considerably more complex than for ground state species, due to the fact that much fewer empirical data about excited state geometries are available and that geometry optimization on the CI level, which is a prerequisite for all calculations of excited state properties, is by no means simple. In this paper we discuss qualitative models, which may be helpful in locating minima on excited state potential surfacesmethods and results for calculations of excited state properties at various levels of sophistication; particular emphasis is laid on sudden polarization phenomena, cis-trans isomers of acetylene in its excited states, the pyramidalization of the carbonyl group, excited states of aromatic compounds (TICT states) andtheoretical treatments of radiative and non-radiative deactivation of excited states.