RESTRUCTURING METHOD FOR THE NEGATIVE SIGN PROBLEM IN QUANTUM SPIN SYSTEMS

We present detailed discussion on a new approach we proposed in a prev ious paper to numerically study quantum spin systems. This method, whi ch we will call re-structuring method hereafter, is based on rearrange ment of intermediate states in the path integral formulation. We obser ved our approach brings remarkable improvement in the negative sign pr oblem when applied to one-dimensional quantum spin-1/2 system with nex t-nearest-neighbor interactions. In this paper we add some description s on our method and show results from analyses by the exact diagonaliz ation and by the transfer matrix method of the system on a small chain . These results also indicate that our method works quite effectively.