Quantum chemical studies of Cr atoms on superfluid He nanodroplets

Full text: He nanodroplets (HeN) provide a superfluid quantum matrix at 0.4 K. Single atoms or molecules doped on HeN can be investigated and used to synthesize nanostructures that may be deposited on surfaces. The location of the dopant on HeN affects the amount of spectroscopic perturbation and the formation of nanostructures on HeN. Cr has outstanding magnetic properties due to the septet ground state. In combination with He, a weak van der Waals molecule is formed which is challenging to describe theoretically. We calculated the Cr-He pair potential curve with different post Hartree-Fock methods. CCSD(T), CI, and multireference perturbation theory (RS) were applied, all including relativistic Douglas-Kroll corrections. After counterpoise correction we extrapolated to the basis set limit. The pair potential is applied to calculate the so-called Ancilotto parameter and to DFT calculations for the He density. Both methods indicate that Cr resides inside HeN. Our group also investigates the Cr-HeN complex experimentally by means of mass and laser spectroscopy. First experimental results will be reported besides the theoretical calculations. (author)