LAUSR

Abstract In order to investigate the electronic correlation effects in the ionization potentials of small lithium clusters, we obtain accurate ground-state energies using the diffusion quantum Monte Carlo simulation. We decompose both the adiabatic and vertical ionization potentials of the clusters into physical components to analyze the nature of the superalkali characteristics of the lithium clusters. We find that the electron-correlation contribution to the ionization potential is mostly canceled out by the orbital relaxation with net contribution less than 0.5 eV. The superalkali characteristics of the clusters is basically determined by the electrostatic and exchange interactions.