Generalized Moment Method for Gap Estimation and Quantum Monte Carlo Level Spectroscopy.
We formulate a convergent sequence for the energy gap estimation in the worldline quantum Monte Carlo method. The ambiguity left in the conventional gap calculation for quantum systems is eliminated. Our estimation will be unbiased in the low-temperature limit, and also the error bar is reliably estimated. The level spectroscopy from quantum Monte Carlo data is developed as an application of the unbiased gap estimation. From the spectral analysis, we precisely determine the Kosterlitz-Thouless quantum phase-transition point of the spin-Peierls model. It is established that the quantum phonon with a finite frequency is essential to the critical theory governed by the antiadiabatic limit, i.e., the k=1 SU(2) Wess-Zumino-Witten model.
Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.|Department of Physics, University of Tokyo, Tokyo 113-0033, Japan.
Hidemaro
H
Suwa
Department of Physics, University of Tokyo, Tokyo 113-0033, Japan.|Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan.
Synge
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Todo