Visualization of quantum fluctuations by superposition of optimized nonorthogonal Slater determinants

Abstract

Electronic states in the one-dimensional (1D) doped Hubbard model are described by superposition of optimized nonorthogonal Slater determinants (S-dets). Analysis on the S-dets allows us to visualize quantum fluctuations. In the weak and intermediate interaction regimes, quantum fluctuations are described by translation and breathing motions of spin-charge coupled defects called polarons as well as spin-charge decoupled defects called holons and spinons. In the strong-interaction regime, on the other hand, spin and charge fluctuations are mostly separated as spinons and holons, especially in the lightly doped systems $(\ensuremath{\delta}=0.08)$. In the highly doped systems $(\ensuremath{\delta}=0.24)$, polarons also play an important role. Finally, it is shown that in the 1/3-filled systems, the concepts of holon, spinon, and polaron do not work anymore. The electronic structure is qualitatively described by mixtures of two different density waves having triple periodicity to the lattice. The domains of these different density waves make quantum fluctuations.