Regensburg 2004 – scientific programme
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TT: Tiefe Temperaturen
TT 32: Theoretische Modelierung von Materialien mit korrelierten Elektronen
TT 32.9: Talk
Friday, March 12, 2004, 12:15–12:30, H18
Energy of the Mott insulator - 10th order perturbation theory extended to infinite order using QMC — •Nils Blümer1 and Eva Kalinowski2 — 1Institut für Physik, Johannes-Gutenberg-Universität, 55099 Mainz — 2FB Physik, Philipps Universität, 35032 Marburg
Of fundamental interest in solid state theory is the correlation induced Mott-Hubbard metal-insulator transition (MIT) between a paramagnetic metal and a paramagnetic insulator. Much progress has been made within the last decade by application of the nonperturbative dynamical mean-field theory to the frustrated one-band Hubbard model with semielliptic density of states. In particular, a coexistence region of metallic and insulating solutions has been established at low temperatures.
Only recently, numerical energy estimates have been obtained with high enough precision for reliably pinpointing the first order MIT line. Even higher accuracy is reached in this work for the ground state insulator using 10th order perturbation theory (PT) and an improved quantum Monte Carlo (QMC) scheme which treats the high-frequency part of the self-energy exactly. Extrapolating the PT coefficients, we obtain a continuous estimate of the energy of the insulating phase with precision O(10−5) throughout its stability region. Analyzing the critical behavior, we determine the (lower) stability edge as Uc1≈ 1.19 × bandwidth.