QUANTUM-CHEMICAL STUDY OF ELECTRONIC AND DYNAMIC PROPERTIES OF METAL AND MIXED NONSTOICHIOMETRIC CLUSTERS

The aim of this contribution is to show that quantum chemistry has sui table tools to extract the specific properties of small metallic and m ixed non-stoichiometric clusters which cannot be obtained by extrapola tion from the bulk properties to the atom. For this purpose, first the main features of the methods used for the calculations of the ground and excited states of clusters valid at zero temperature (T = 0) will be sketched and the factors determining accuracy of results will be po inted out. The structural and optical response properties of cationic Na-n(+) clusters as a function of size will be presented and compared with experimental data. The series of non-stoichiometric alkali-halide clusters containing single and multiple excess electrons will serve a s prototypes to study a possible ''metal-insulator transition'' and '' segregation into metallic and ionic parts'' in finite systems. Second, an outline of ab initio molecular dynamics methods based on gradient corrected density functional approach with gaussian basis used fbr det ermination of temperature dependent ground state properties will be pr esented. Different temperature behavior of distinct type of structures will be illustrated on an example of Li-9(+) cluster.