Electron correlations and silicon nanocluster energetics
  The first-principle prediction of nanocluster stable structure is often hampered by the existence of many isomer configurations with energies close to the ground state. This fact attaches additional importance to many-electron effects going beyond density functional theory (DFT), because their contributions may change a subtle energy order of competitive structures. To analyze this problem, we consider, as an example, the energetics of silicon nanoclusters passivated by hydrogen Si$_{10}$H$_{2n}$ with $0\le n\le 11$, the structure of which varies with passivation from compact to loose-packed, similar to branching polymers. Our calculations performed by the DFT, hybrid functionals and Hartree-Fock (H-F) methods, as well as by the GW approximation (GWA), confirm a considerable sensitivity of structure prediction and isomer energy ordering to many-electron effects and show some results which may be obtained with the methods less computationally demanding than the GWA. 
N.L. Matsko, Yu.A. Uspenskii, E.V. Tikhonov, V.S. Baturin, S.V.   Lepeshkin
cond-mat.mes-hall physics.chem-ph