Study on Ground States of Quantum Spin Systems by Restructuring Method

概要

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We present a new method to study the ground state of quantum spin systems using Monte Carlo techniques. Our idea is to obtain the coefficients in the expansion of the ground state, both their magnitudes and their relative signs, from measurements of the normalized frequencies of each state on the boundary in the Trotter direction. This knowledge of the ground state helps us to calculate some complicated physical quantities such as time correlation functions. As a concrete example we study spin ladder systems with antiferromagnetic intrachain nearest neighbor interactions, whose ground states may be equivalent to that of the spin 1 chain. For the ladder with ferromagnetic rungs, we show how to determine the magnitudes and relative signs of the coefficients in the expansion. We also demonstrate that we can calculate the time correlation function using these Monte Carlo data and analytical techniques. When the ladder has antiferromagnetic rungs, we examine White's claim that the diagonally situated pair of spins are mostly triplet states in the ground state. Our results strongly suggest that the system has hidden order which is constructed by the specially aligned triplet states of diagonal pairs.
理論物理学刊行会の論文
1996-07-25