English

Efficient generation of series expansions for $\pm J$ Ising spin-glasses in a classical or a quantum (transverse) field

Disordered Systems and Neural Networks 2018-01-03 v1

Abstract

We discuss generation of series expansions for Ising spin-glasses with a symmetric ±J\pm J (i.e. bimodal) distribution on d-dimensional hypercubic lattices using linked-cluster methods. Simplifications for the bimodal distribution allow us to go to higher order than for a general distribution. We discuss two types of problem, one classical and one quantum. The classical problem is that of the Ising spin glass in a longitudinal magnetic field, hh, for which we obtain high temperature series expansions in variables tanh(J/T)\tanh(J/T) and tanh(h/T)\tanh(h/T). The quantum problem is a T=0T=0 study of the Ising spin glass in a transverse magnetic field hTh_T for which we obtain a perturbation theory in powers of J/hTJ/h_T. These methods require (i) enumeration and counting of \textit{all} connected clusters that can be embedded in the lattice up to some order nn, and (ii) an evaluation of the contribution of each cluster for the quantity being calculated, known as the weight. We discuss a general method that takes the much smaller list (and count) of all no free-end (NFE) clusters on a lattice up to some order nn, and automatically generates all other clusters and their counts up to the same order. The weights for finite clusters in both cases have a simple graphical interpretation that allows us to proceed efficiently for a general configuration of the ±J\pm J bonds, and at the end perform suitable disorder averaging. The order of our computations is limited by the weight calculations for the high-temperature expansions of the classical model, while they are limited by graph counting for the T=0T=0 quantum system. Details of the calculational methods are presented.

Keywords

Cite

@article{arxiv.1709.03609,
  title  = {Efficient generation of series expansions for $\pm J$ Ising spin-glasses in a classical or a quantum (transverse) field},
  author = {R. R. P. Singh and A. P. Young},
  journal= {arXiv preprint arXiv:1709.03609},
  year   = {2018}
}

Comments

14 pages, 7 figures and 2 tables