Theoretical studies of atom - diatom inelastic collisions under magnetic field: applications in Astro-chemistry and in the field of molecular cooling and trapping

Tremendous progress in experimental production and trapping of ultracold neutral and ionic molecules has been achieved over the past few years which even allowed the production of molecular Bose-Einstein condensates. These ultracold molecules samples have potential applications in many different fields, such as precision spectroscopic measurements or quantum information storage and processing. The optimization of the cooling processes and the trapping techniques also stimulated a great number of theoretical studies. Many of them are dedicated to inelastic scattering of molecules in collisions with ³He atoms (buffer gas cooling method). The potential energy surface of the ground state of the He-MnH(X ⁷Σ⁺) van der Waals complex is presented, followed by the calculations of the bound states of this system and the Zeeman relaxation in function of the magnetic field. In the field of astro-chemistry, a quantum mechanical investigation of rotational energy transfer in cold collisions of CH⁺ with ⁴He atoms is presented. (author)