STRONG-COUPLING EXPANSIONS FOR THE PURE AND DISORDERED BOSE-HUBBARD MODEL

摘要: A strong-coupling expansion for the phase boundary of (incompressible) Mott insulator is presented Bose-Hubbard model. Both pure case and disordered are examined. Extrapolations series expansions provide results that as accurate Monte Carlo simulations agree with exact solutions. The shape difference between Kosterlitz-Thouless critical behavior in one-dimension power-law singularities higher dimensions arises naturally this expansion. Bounded disorder distributions produce a ``first-order'' kink to thermodynamic limit because presence Lifshitz's rare regions. \textcopyright{} 1996 American Physical Society.