arXiv subjects

H. Kitatani

Publications and source records attributed to H. Kitatani.

4 recordsLinked to original sources

arXiv2006

The Nature of the Probability Distribution Function of the Local Energy in Ising Spin Glass

The nature of the probability distribution function of the local energy in the $\pm J$ Ising model has been investigated. At finite temperature, it has been derived that the probability distribution function must satisfy several relations at $p=1/2$ ($p$ is the concentrationof the ferromagnetic bond) and at Nishimori-line, respectively on any lattice in any dimension. They relate the probability distribution function corresponding to the local energy lower than $-\tanh (K)$ with that corresponding to the local enegy greater than $-\tanh (K)$. ($K$ is the inverse temperature.) The present results at Nishimori-line are, in a sense, generalization of Nishimori's result about the internal energy obtained by the local gauge transformation. Moreover, from the numerical calculation in the two-dimentional $\pm J$ Ising model, it is found that, in a certain temperature region, the probability distribution function of the local energy has several peaks which are related to the patterns of frustration around a bond of the lattice.

cond-mat.dis-nn↗

arXiv2002

The specific heat of the rwo-dimensional +/-J Ising model

The specific heat of the two-dimensional $\pm J$ Ising model has been investigated by the numerical transfer matrix method and Monte Carlo simulations from a new point of view. The region where a part of the specific heat takes the negative value has been investigated, which is characteristic of frustrated systems and reflects the non-trivial degeneracy of the ground state. The region mentioned above is found to be fairly large in the $p-T$ plane ($p$ is the concentration of the ferromagnetic bond and $T$ is the temperature). Moreover, it includes the Nishimori line. Namely, it includes a part of the paramagnetic-ferromagnetic phase boundary, on which the specific heat cannot diverge. The present result indicates that the specific heat does not diverge at least on a part of the paramagnetic-ferromagnetic phase boundary above the multicritical point, which is in conflict with previous results.

cond-mat.dis-nn↗

arXiv2001

Reply to Comment on 'A new method to calculate the spin-glass order parameter of the two-dimensional $\pm J$ Ising model'

In response to the comment made by Dr. Shirakura {\it et al} (cond-mat/0011235), we explain that their scaling forms of the order parameter distribution are inadequate. We then present an appropriate scaling form of the order parameter distribution, which gives a good scaling plot of the order parameter distribution itself and also gives consistent results with our pevious results[1].

cond-mat.dis-nn↗

arXiv2000

A New Method to Calculate the Spin-Glass Order Parameter of the Two-Dimensional +/-J Ising Model

A new method to numerically calculate the $n$th moment of the spin overlap of the two-dimensional $\pm J$ Ising model is developed using the identity derived by one of the authors (HK) several years ago. By using the method, the $n$th moment of the spin overlap can be calculated as a simple average of the $n$th moment of the total spins with a modified bond probability distribution. The values of the Binder parameter etc have been extensively calculated with the linear size, $L$, up to L=23. The accuracy of the calculations in the present method is similar to that in the conventional transfer matrix method with about $10^{5}$ bond samples. The simple scaling plots of the Binder parameter and the spin-glass susceptibility indicate the existence of a finite-temperature spin-glass phase transition. We find, however, that the estimation of $T_{\rm c}$ is strongly affected by the corrections to scaling within the present data ($L\leq 23$). Thus, there still remains the possibility that $T_{\rm c}=0$, contrary to the recent results which suggest the existence of a finite-temperature spin-glass phase transition.

cond-mat.dis-nn↗