A b i n i t i o calculations of the electronic structure of small Nan, Na+n, Kn, and K+n clusters (n≤6) including core–valence interaction

The electronic structure of small Nan, Na+n, Kn, and K+n alkali clusters (n≤6) is investigated using nonempirical core pseudopotentials, configuration interaction within a 3s/1p/1d Gaussian basis set per atom and including the core–valence interaction through a perturbative treatment. Equilibrium geometries, stabilities, ionization potentials, and fragmentation channels are derived and the role of electronic correlation in small alkali clusters is examined.