  We present realistic multiband calculations of scanning tunneling spectra in
Bi_{2}Sr_{2}CaCu_{2} O_{8+\delta} over a wide doping range. Our modeling
incorporates effects of a competing pseudogap and pairing gap as well as
effects of strong electronic correlations, which are included by introducing
self-energy corrections in the one-particle propagators. The calculations
provide a good description of the two-gap features seen in experiments at low
energies and the evolution of the Van Hove singularity (VHS) with doping, and
suggest a possible quantum critical point near the point where the VHS crosses
the Fermi level.

Superconductivity