Berlin 2001 – scientific programme

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MO: Molekülphysik

MO 7: Posters Wednesday: Theory: Structure and Dynamics

MO 7.6: Poster

Wednesday, April 4, 2001, 12:30–15:00, AT3

Spatial anisotropy and structure of bound states for the He2+ + He interaction — •Emanuele Scifoni, Franco Gianturco, and Francesco Paesani — Lab.Chimica Teorica, Dip.di Chimica NEC, Universita’la Sapienza, p.za A.Moro 5,Roma Italy

Experimental(1) and theoretical(2) studies on large Helium ionized clusters suggest the structure of a ionic dimer surrounded by neutral, Van der Waals bound atoms, whereas an ionic trimer core is found for smaller clusters. The structure of the systems and the relaxation mechanism through which the dimer gets stabilized inside the cluster is the aim of this study. We have carried out accurate calculations (CCSD(T) with aug-cc-pVQZ) to obtain a detailed P.E.S. of system He2+ + He .

The Rigid Rotor system was firstly analyzed, fixing the internuclear dimer distance r to 2.00 a.u., near its equilibrium (2.04 a.u.), and fitting the results by polynomial expansion. Using a Discrete Variable Representation (DVR)(3) approach we have found 13 bound states of the system. Calculations were performed then for the vibrational extention by scanning 7 values of r, obtaining a global He3+ P.E.S..

Quantum calculations on dynamical rates for rovibrational relaxation are in progress and will be presented at the meeting.

(1)Callicoatt,Janda et al.;J.Chem.Phys.105,7872(1996)

(2)Knowles,Murrel;Mol.Phys.87,4(1996) 827-833

(3)Tennyson et al.;Comp.Phys.Comm.86 (1995) 175-198