Physical review. B, Condensed matter
Path-integral theory of the metal-insulator transition in the three-dimensional Hubbard model
Norikazu Tomita, Masahiro Yamazaki, Keiichirō Nasu
Abstract
We study, by using the quantum Monte Carlo simulation of path-integral form, how the gap is developed in the density of state (DOS) and optical conductivity of the three-dimensional half-filled Hubbard model as a function of the temperature. It is shown that the DOS has a coherent peak just on the Fermi level in the high-temperature region. However, it moves to the high-binding-energy side when the temperature is lowered. The DOS just on the Fermi level is decreased as the decrease of the temperature, and eventually, a gap opens in the DOS. The Drude component in the optical conductivity also decreases with temperature, but it can remain relatively large compared to the DOS at the Fermi level, if the DOS is finite there. We show that the experimentally observed photoemission and optical conductivity spectra of ${\mathrm{CaVO}}_{3}$ are explained within the present theoretical framework effectively and consistently.