63011 20190709135510.0 doi 10.1103/PhysRevE.96.032114 sideral 101620 ART-2017-101620 eng (orcid)0000-0002-8215-1413 Azcoiti, Vicente Universidad de Zaragoza Antiferromagnetic Ising model in an imaginary magnetic field 2017 Access copy available to the general public Unrestricted We study the two-dimensional antiferromagnetic Ising model with a purely imaginary magnetic field, which can be thought of as a toy model for the usual ¿ physics. Our motivation is to have a benchmark calculation in a system which suffers from a strong sign problem, so that our results can be used to test Monte Carlo methods developed to tackle such problems. We analyze here this model by means of analytical techniques, computing exactly the first eight cumulants of the expansion of the effective Hamiltonian in powers of the inverse temperature, and calculating physical observables for a large number of degrees of freedom with the help of standard multiprecision algorithms. We report accurate results for the free energy density, internal energy, standard and staggered magnetization, and the position and nature of the critical line, which confirm the mean-field qualitative picture, and which should be quantitatively reliable, at least in the high-temperature regime, including the entire critical line. info:eu-repo/grantAgreement/ES/DGA/E24-2 info:eu-repo/grantAgreement/ES/MINECO/FPA2012-35453 info:eu-repo/grantAgreement/ES/MINECO/FPA2015-65745-P info:eu-repo/semantics/openAccess by http://creativecommons.org/licenses/by/3.0/es/ 2.284 2017 PHYSICS, MATHEMATICAL 7 / 55 = 0.127 2017 Q1 T1 PHYSICS, FLUIDS & PLASMAS 12 / 31 = 0.387 2017 Q2 T2 0.979 2017 Condensed Matter Physics 2017 Q1 Statistical and Nonlinear Physics 2017 Q1 Statistics and Probability 2017 Q2 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Di Carlo, Giuseppe (orcid)0000-0002-4742-4279 Follana, Eduardo Universidad de Zaragoza (orcid)0000-0003-1550-8168 Royo-Amondarain, Eduardo Universidad de Zaragoza 2004 405 Universidad de Zaragoza Dpto. Física Teórica Área Física Teórica 96, 3 (2017), 032114 [11 pp] Phys. rev., E Physical Review E 2470-0045 540414 http://zaguan.unizar.es/record/63011/files/texto_completo.pdf Versión publicada 131237 http://zaguan.unizar.es/record/63011/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:63011 articulos driver 2019-07-09-11:51:13 ARTICLE