Full configuration-interaction study of the metal-insulator transition in model systems

The precursor of the Metal-Insulator transition is studied at ab-initio level in equally-spaced Li-n and Be-n linear chains. In particular, large-size Full Configuration-Interaction (FCI) calculations (up to one billion determinants for Li-8 and half a billion for Be-5) have been performed. At FCI level, it is possible to take into account the different nature of the electronic wavefunction at the different internuclear distances. Several indicators of the Metal-Insulator transition (minimum of the Koopmans energy gap, maximum of the localization and polarizability tensors) are considered and discussed. In is shown that the three considered properties indicate a Metal-Insulator transition at distances that are in remarkable agreement.