(4He)N-Cs2(2¿), N=2 up to 12, clusters: a Hartree-like approach

Abstract

Clusters and droplets of noble gases, mainly Helium, have opened up a new field or research. In particular, the study of medium-size complexes has been motivated by striking phenomena like superfluidity [1]. It is related with the completely different spectra of molecules embedded in this kind of clusters, depending on the bosonic or fermionic nature of the solvent: in the former case it is a well-defined profile, while in the latter any structure is lost. In this work we study complexes formed by a diatomic Cs2 molecule plus an ensemble of N 4He atoms, with N=2 up to 12. In order to search the ground state wave-function of the system we have employed Hartree Quantum-Chemistry-like calculations [2], assuming adiabaticity in the diatomic stretch and decoupling of the diatomic rotation from the helium atoms. The PES is described through a sum of pairwise interactions and we have used an ab initio scheme for the Cs2-He potential. We will show energetic and structural aspects of the clusters, trying to understand the arrangement of the impurity with respect to the helium cloud. This is a part of a most comprehensive study that includes also a fermionic helium environment, whose work is being currently in progress. The overall objective of the this research is to clarify the effect of the spin statistic in the spectrum of the impurity (see Refs. 3,4 for more details). 1) S. Grebenev, J. P. Toennies, and A. F. Vilesov, Science 279, 2083 (1998). 2) M. P. de Lara-Castells, D. López-Durán, G. Delgado-Barrio, P. Villarreal, C. Di Paola, F. A. Gianturco, and J. Jellinek, Phys. Rev. A 71, 033203 (2005). 3) D. López-Durán, M. P. de Lara-Castells, G. Delgado-Barrio, P. Villarreal, C. Di Paola, F. A. Gianturco, and J. Jellinek, J. Chem. Phys. 121, 2975 (2004). 4) D. López-Durán, M. P. de Lara-Castells, G. Delgado-Barrio, P. Villarreal, C. Di Paola, F. A. Gianturco, and J. Jellinek, Phys. Rev. Lett. 93, 053401 (2004).