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A ``ballistic-search'' algorithm is presented which allows the identification of clusters (or funnels) of ground states in Ising spin glasses even for moderate system sizes. The clusters are defined to be sets of states, which are connected…

Disordered Systems and Neural Networks · Physics 2009-10-31 Alexander K. Hartmann

We present an algorithm which calculates groundstates of Ising spin glasses approximately. It works by randomly selecting clusters of spins which exhibit no frustrations. The spins which were not selected, contribute to the local fields of…

Condensed Matter · Physics 2015-06-25 A. K. Hartmann

Large numbers of ground states of two-dimensional Ising spin glasses with periodic boundary conditions in both directions are calculated for sizes up to 40^2. A combination of a genetic algorithm and Cluster-Exact Approximation is used. For…

Disordered Systems and Neural Networks · Physics 2009-10-31 Alexander K. Hartmann

Ground states of three-dimensional EA Ising spin glasses are calculated for sizes up to 14^3 using a combination of a genetic algorithm and cluster-exact approximation. For each realization several independent ground states are obtained.…

Disordered Systems and Neural Networks · Physics 2015-06-25 Alexander K. Hartmann

Ground states of four-dimensional (d=4) EA Ising spin glasses are calculated for sizes up to 7x7x7x7 using a combination of a genetic algorithm and cluster-exact approximation. The ground-state energy of the infinite system is extrapolated…

Disordered Systems and Neural Networks · Physics 2009-10-31 Alexander K. Hartmann

Ground states of 3d EA Ising spin glasses are calculated for sizes up to $14^3$ using a combination of genetic algorithms and cluster-exact approximation . The distribution $P(|q|)$ of overlaps is calculated. For increasing size the width…

Disordered Systems and Neural Networks · Physics 2009-10-30 Alexander K. Hartmann

Ground states of 3d EA Ising spin glasses are calculated for sizes up to 14^3 using a combination of a genetic algorithm and Cluster-Exact Approximation. Evidence for an ultrametric structure is found by studying triplets of independent…

Disordered Systems and Neural Networks · Physics 2009-10-31 Alexander K. Hartmann

Unbiased samples of ground states were generated for the short-range Ising spin glass with Jij=+/-1, in three dimensions. Clustering the ground states revealed their hierarchical structure, which is explained by correlated spin domains,…

Disordered Systems and Neural Networks · Physics 2009-10-31 Guy Hed , Alexander K. Hartmann , Dietrich Stauffer , Eytan Domany

Due to an extremely rugged structure of the free energy landscape, the determination of spin-glass ground states is among the hardest known optimization problems, found to be NP-hard in the most general case. Owing to the specific structure…

Disordered Systems and Neural Networks · Physics 2011-11-10 Martin Weigel

A new approach known as flat histogram method is used to study the +/-J Ising spin glass in two dimensions. Temperature dependence of the energy, the entropy, and other physical quantities can be easily calculated and we give the results…

Statistical Mechanics · Physics 2009-10-31 Zhi Fang Zhan , Lik Wee Lee , Jian-Sheng Wang

The genetic cluster-exact approximation algorithm is an efficient method to calculate ground states of EA spin glasses. The method can be used to study ground-state landscapes by calculating many independent ground states for each…

Disordered Systems and Neural Networks · Physics 2007-05-23 Alexander K. Hartmann

We propose a new Ising spin glass model on $Z^d$ of Edwards-Anderson type, but with highly disordered coupling magnitudes, in which a greedy algorithm for producing ground states is exact. We find that the procedure for determining…

adap-org · Physics 2015-06-30 C. M. Newman , D. L. Stein

Large numbers of ground states of 3d EA Ising spin glasses are calculated for sizes up to 10^3 using a combination of a genetic algorithm and Cluster-Exact Approximation. A detailed analysis shows that true ground states are obtained. The…

Disordered Systems and Neural Networks · Physics 2009-10-31 Alexander K. Hartmann

Using mappings to computer-science problems and by applying sophisticated algorithms, one can study numerically many problems much better compared to applying standard approaches like Monte Carlo simulations. Here, using calculations of…

Disordered Systems and Neural Networks · Physics 2007-05-23 A. K. Hartmann

We derive exact analytical expressions for the ground-state energy and entropy of the two-dimensional $\pm J$ Ising spin glass, uncovering a nested hierarchy of frustrations. Each level in this hierarchy contributes through the kernel and…

Disordered Systems and Neural Networks · Physics 2025-04-10 Chaoming Song

A method is presented, which allows to sample directly low-temperature configurations of glassy systems, like spin glasses. The basic idea is to generate ground states and low lying excited configurations using a heuristic algorithm. Then,…

Disordered Systems and Neural Networks · Physics 2009-11-07 Alexander K. Hartmann , Federico Ricci-Tersenghi

A constructive scheme for determining pure states (clusters) at very low temperature in the 3-spins glass model on a random lattice is provided, in full agreement with Parisi's one step replica symmetry breaking (RSB) scheme. Proof is based…

Statistical Mechanics · Physics 2009-11-07 S. Cocco , O. Dubois , J. Mandler , R. Monasson

Computing the ground state of Ising spin-glass models with p-spin interactions is, in general, an NP-hard problem. In this work we show that unlike in the case of the standard Ising spin glass with two-spin interactions, computing ground…

Disordered Systems and Neural Networks · Physics 2015-03-17 Creighton K. Thomas , Helmut G. Katzgraber

With the help of EXACT ground states obtained by a polynomial algorithm we compute the domain wall energy at zero-temperature for the bond-random and the site-random Ising spin glass model in two dimensions. We find that in both models the…

Disordered Systems and Neural Networks · Physics 2009-10-28 N. Kawashima , H. Rieger

We employ a novel algorithm using a quasi-exact embedded-cluster matching technique as minimization method within a genetic algorithm to reliably obtain numerically exact ground states of the Edwards-Anderson XY spin glass model with…

Disordered Systems and Neural Networks · Physics 2007-05-23 Martin Weigel , Michel J. P. Gingras
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