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The Ising free‐energy functional
Author(s) -
Campbell Loudon,
Matsen F. A.
Publication year - 1996
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1996)59:5<391::aid-qua3>3.0.co;2-t
Subject(s) - ising model , condensed matter physics , coupling constant , ferromagnetism , energy functional , physics , phase transition , order (exchange) , energy (signal processing) , constant (computer programming) , superconductivity , mathematical physics , quantum mechanics , computer science , finance , economics , programming language
We show that the Ising free‐energy functional f ( T, X ) yields a second‐order phase transition. The value of X , a generalized order parameter, which minimizes the functional is the real‐order parameter, Ω = tanh[Ω( T C / T )] where T c = J /(2 k ) and J is the Ising coupling constant. The Ising theory is applicable to the second‐order phase transitions in ferromagnets, ferroelectrics, and superconductors. The constant temperature slices of f ( T, X ) yields the Ising functional which is valid over the entire range of T and which is identical to the Landau functional for T/T C close to unity. © 1996 John Wiley & Sons, Inc.