The Influence of Excess Ammonia on the Mechanism of the Reaction of Boron Trichloride with Ammonia-An Ab Initio Molecular Dynamics Study This work was supported by the Deutsche Forschungsgemeinschaft in the framework of the Sonderforschungsbereich 408 "Anorganische Festkörper ohne Translationssymmetrie". We thank Mauro Boero from the Joint Research Center for Atom Technology, Tsukuba (Japan) for the reoptimization of the Martins-Troullier pseudopotentials for boron and chlorine, as well as the John-von-Neumann-Institut für Computing, Jülich, for making computer time available to us.