The Resonating-Valence-Bond Ground State of Li Nanoclusters
  We have performed Diffusion Quantum Monte Carlo simulations of Li clusters showing that Resonating-Valence-Bond (RVB) pairing correlations between electrons provide a substantial contribution to the cohesive energy. The RVB effects are identified in terms of electron transfers from s- to p-like character, constituting a possible explanation for the breakdown of the Fermi liquid picture observed in recent high resolution Compton scattering experiments for bulk Li. 
D. Nissenbaum, L. Spanu, C. Attaccalite, B. Barbiellini, A. Bansil