Modelling of helium ionic clusters: structure, spectra, thermodynamics and dynamics.

Abstract:
The main goal of this project is to build up reliable semiempirical models of interactions in medium-size and large ionic helium clusters, Hen+, and to use them in a series of calculations of the geometric and electronic structure, thermodynamicproperties, photoabsorption, and dynamics of these cluster ions up to the size of 30 atoms. The models will employ both various extensions of the well known diatomics-in-molecules methods as well as the more promising triatomics-in-molecules approach. The work comprise accurate ab initio calculations of the electronic ground and the first two excited states in He3+, their use in building up the semiempirical models for larger clusters, tests of these models by a comparison with additional ab initiodata calculatedfor He3+, He4+, and He5+ and finally, extensive calculations of Hen+ structure, photoabsorption, thermodynamics, and fragmentation dynamics from vibrationally and electronically excited states.