Absence of Hysteresis at the Mott-Hubbard Metal-Insulator Transition in Infinite Dimensions

The nature of the Mott-Hubbard metal-insulator transition in the infinite-dimensional Hubbard model is investigated by quantum Monte Carlo simulations down to temperature $T=W/140$ ( $W=\mathrm{bandwidth}$). Calculating with significantly higher precision than in previous work, we show that the hysteresis below $T_{\mathrm{IPT}}\simeq 0.022W$, reported in earlier studies, disappears. Hence the transition is found to be continuous rather than discontinuous down to at least ${T=0.325T}_{\mathrm{IPT}}$. We also study the changes in the density of states across the transition, which illustrate that the Fermi liquid breaks down before the gap opens.