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 Lin and Ben linear chains. In particular, large-size Full Configuration-Interaction (FCI) calculations (up to one billion determinants for Li8 and half a billion for Be5) 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.