Bernd Ensing first saw the light of day on February 16, 1972 in Delfzijl (the Netherlands) and grew up in a friendly village named Wagenborgen, which lies somewhere in the flat and green countryside of the Groningen province. In 1990, he completed the havo at the Fivel-college in Delfzijl and a year later he graduated at the atheneum at the same college. He moved to Enschede to study Chemical Technology at the technical university of Twente. Although educated to become an chemical engineer, he choose his mayor in the field of chemical physics at the group of professor Wim Briels, who send him to Sweden for a three-month traineeship at the computational chemistry group of professor Kersti Hermansson, situated at the Uppsala University. Here, he performed his first calculations and completed a study entitled "ab initio and DFT computations of H absorption on reconstructed MgO(111) surfaces obtained from molecular dynamics snapshots", which led to his first scientific publication. In August 1996, he graduated his Master of Science with a study on argon adsorption in the pores of AlPO-5 zeolites, which he completed partly in Hermansson's group in Uppsala and in the chemical physics group in Enschede. Two months later he moved to Amsterdam and started his Ph.D. study on first principles dynamics simulations of solvent effects on chemical reactions, in the theoretical chemistry group of professor Evert Jan Baerends, of which this thesis is the result. In November 2002, he will move to Philadelphia to start a post-doctoral study in the group of professor Mike Klein at the University of Pennsylvania. In the mean time he hopes to one morning wake up and find himself being able to play as good a saxophone as Charly Bird Parker...