Variational cluster approach for strongly correlated lattice bosons in the superfluid phase

Article

关键词: ENERGY-FUNCTIONAL APPROACH;    GROUND-STATE ENERGY;    MANY-BODY PHENOMENA;    SELF-ENERGY;    GAPLESS APPROXIMATIONS;    ENTROPY PRINCIPLE;    SYSTEMS;    RENORMALIZATION;    INSULATOR;    GAS;   

DOI  :  10.1103/PhysRevB.83.134507

来源: SCIE

【 摘 要 】

We extend the variational cluster approach to deal with strongly correlated lattice bosons in the superfluid phase. To this end, we reformulate the approach within a pseudoparticle formalism, whereby cluster excitations are described by particlelike excitations. The approximation amounts to solving a multicomponent noninteracting bosonic system by means of a multimode Bogoliubov approximation. A source-and-drain term is introduced in order to break U(1) symmetry at the cluster level. We provide an expression for the grand potential, the single-particle normal and anomalous Green's functions, the condensate density, and other static quantities. As a first nontrivial application of the method we choose the two-dimensional Bose-Hubbard model and evaluate results in both the Mott and the superfluid phases. Our results show an excellent agreement with quantum Monte Carlo calculations.

【 授权许可】

Free