Seminarium "Modeling of Complex Systems"

Matter in our Galaxy evolves from extremely diluted gas, through molecular clouds, and star-forming regions to stars and their planetary systems. The pre-stellar phase is characterized by a mixture of gas and dust in low density (104 atoms/cm3) and temperature (10-30 K) conditions. Observing atoms and molecules in molecular clouds provides a unique glimpse into an extreme environment whose conditions are difficult to match even in sophisticated laboratories. In course of this lecture, we show a connection between the microscopic processes studied in laboratories on Earth and our understanding of phenomena in different space environments.The bulk of interstellar molecules have been detected by observation of microwave emission from rotationally excited molecules.Theoretical predictions of spectroscopic parameters such as rotational constants and vibrational frequencies by quantum calculations play an important role in guiding spectroscopic and astronomical studies of molecules, as we demonstrate using a few different examples.The main question is: how are these molecules formed? Here, we present the possible cold-chemistry routes leading to selected sulfur-containing molecules of astrophysical significance by modeling of the relevant reaction network using quantum chemical calculations.