A Monte Carlo study on distribution of CuO chains in YBa2Cu3O6+2c

Chain length probability distribution — equivalence of ASYNNNI and 1d Ising model

“…This result was derived, in the case of low temperatures, by studying the structure of low energy levels and was confirmed in Monte Carlo numerical simulations for Ortho I and II structural phases. The result was confirmed for the Ortho II structural phase at a temperature of T ≈ 450 K, where T is the oxygen equilibrium temperature [18], and in the case of the Ortho I phase for temperatures as high as T ≈ 1800 K [17]. Furthermore, it was concluded that this specific form of the chain probability distribution should be valid for all oxygen concentrations, and all temperatures where the orthorhombic structures are stable, except in the close vicinity of the line of the critical points [18].…”

“…[17] to be valid for the ASYNNNI model at low temperatures. Using expression (3) and the definition of the cluster microstate probabilities in the cluster variation method [32]: where E is the energy of the cluster in its -th cluster microstate, and Z is its partition function, the chain length probability can be cast in the following form:…”

“…Recently, the plain ASYNNNI model has been employed in extensive studies of the properties of the distribution of the CuO chains with respect to chain length [17,18]. It was found that the chain length probability distribution satisfies the simple geometrical law [17] i.e.…”

“…It was found that the chain length probability distribution satisfies the simple geometrical law [17] i.e. that the distribution is determined by only one parameter.…”

“…[17]. for the chain length probability distribution of Cu-O chains formed in the basal planes of YBCO material, studied in the frame of the ASYNNNI model.…”