Theory and Computation Group on Quantum Structures
and Quantum Dynamics

Department of Chemistry, The University of Rome "La Sapienza".
Group Leader : Prof. Franco A. Gianturco.

The research group in Rome is currently investigating several aspects of the non-classical structures and the quantum dynamics which are relevant to molecular systems, neutral and ionized, that undergo collisional cooling, reactive collisions and interaction processes at ultra-low energy. The latter situation is meant to describe the possible molecular environment in a cold trap or the possible formation of new molecules in conditions close to or at the existence of Bose Einstein condensates of atomic gases.

In particular, the research is directed at obtaining a realistic description of the interaction forces between simple molecular species like HF, LiH, CO ,NH, Li2 and others with a buffer helium gas that could be used to induce sympathetic cooling of the above molecular species. This means that it becomes important to be able to obtain the cooling rates for such molecular species in excited rotovibrational states when colliding with He at ultra-low energies. Such quantities have to be obtained from a realistic knowledge of the full potential energy surfaces, of the effect of external magnetic fields on their hyperfine interactions (when existing) and from a rigorous treatment of the coupled channel scattering problem at such limiting energy values.

Furthermore, similar molecular partners could also be undergoing chemical reactions at the trap conditions, thereby revealing unexpected properties of the reactive cross sections and of related observables when the number of contributing partial waves is drastically reduced as is the case for scattering processes in the range of the micro and nano-kelvin regimes. Also in such cases the group of Prof. Gianturco is involved in producing rigorous quantum reactive cross sections for systems like F + H2 = HF + H , or for Li + H2 + LiH + H or for Li+ + H2 + LiH+ +H .

Finally, the interests of the group in Rome have also been directed at studying the scattering of electrons from molecular gases containing polyatomic molecules when the collision energies get close to the ultra-cold collision regimes. Here also the corresponding observables exhibit an unusual behaviour and their theoretical study allows one to make contact with the recent experimental studies on the dynamics of cold electrons interacting with molecular systems. A similar class of processes is also provided by the scattering of cold positron beams with molecular polyatomic targets, where the annihilation efficiency of the antiparticle, usually revealed by detecting the intensity of the gamma photon emission, is found by experiments to be very strongly dependent on the structural features of the molecular target and on the temperature of the latter in the positron trap.

In sum, one can say that the general involvement of the Rome research group with the scientific area that are present in the CATS project deals with the accurate quantum treatment of inelastic and reactive molecular collision processes at ultra-low collision energies and involving a broad range of molecular species, from the simple diatomics to fairly large polyatomic gases.