Electronic structure and geometries of heteroatomic clusters.

Abstract

The equilibrium geometries and the electronic structure of heteroatomic clusters involving alkali-metal-atom hosts and aluminum and magnesium impurity atoms have been studied using the self-consistent-field linear combination of atomic orbitals--molecular orbital method. The total energies of the clusters have been calculated by including exchange interaction within the unrestricted Hartree-Fock approximation and the correlation contribution within using the configuration interaction involving the double excitations of the valence electrons. The heteroatoms are found to have significant effect on the topology of the host clusters. The relative stabilities and ionization potentials of heteroatomic clusters exhibit odd-even alternation in agreement with experimental data. The evolution of the binding energies of the heteroatom with cluster size testifies to the delocalized nature of the electrons of the host cluster. While the energy gained in adding an additional alkali-metal atom to the existing heteroatomic cluster continues to oscillate with cluster size, the heteroatom binding energy varies monotonically.