TRANSFER-MATRIX CALCULATIONS OF THE SPIN 1/2 ANTIFERROMAGNETIC XXZ MODEL ON THE 4X2 TRIANGULAR LATTICE USING THE FRACTAL DECOMPOSITION

The fractal decomposition of exponential operators proposed by Suzuki, which is a new category of the generalized Trotter decomposition valid up to higher orders, is examined with transfer-matrix calculations of the spin 1/2 antiferromagnetic XXZ model on the 4x2 triangular lattice. The dependence of correction terms on the Trotter number and temperature are studied. This dependence confirms rapid convergence of the fractal decomposition. The negative-sign problem arising in quantum Monte Carlo simulations is also discussed from the present new point of view.