caa a22 4500 477058744 CHVBK 20180405111354.0 cr unu---uuuuu 170330e19960101xx s 000 0 eng 10.1007/BF02069239 doi (NATIONALLICENCE)springer-10.1007/BF02069239 Sabirov R. V. I. Lenin Moscow Pedagogical University, USSR aut One self-consistent closure for chains of equations for Green's functions. An anisotropic heisenberg model [Elektronische Daten] [R. Sabirov] This article present a self-consistent approach to computation of the correlation function in the method of Green's functions. The basis for the approach is representation of the desired Green's function in the form of a chain of fractions that is subsequently closed. The closure is based on the use of concrete relations imposed on the higher-order correlation functions. General expressions for the correlation functions and conditions for self-consistency of the computations are presented. The method has been tested by computing the magnetization and critical temperature in a Heisenberg model with arbitrary anisotropy parameter. We obtain general expressions for these quantities. The critical temperature obtained is less than the corresponding value given by the molecular-field approximation. The latter approximation also leads to an overestimate of the magnetization values. It is shown that no critical transition is possible for any value of the anisotropy parameter. The corresponding inequalities are obtained. The method is compared with a method for self-consistent computation of correlation functions that was proposed earlier by the author. Plenum Publishing Corporation, 1996 Russian Physics Journal Kluwer Academic Publishers-Plenum Publishers 39/1(1996-01-01), 41-47 1064-8887 39:1<41 1996 39 11182 https://doi.org/10.1007/BF02069239 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02069239 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Sabirov R. V. I. Lenin Moscow Pedagogical University, USSR aut NATIONALLICENCE 773 0- Russian Physics Journal Kluwer Academic Publishers-Plenum Publishers 39/1(1996-01-01), 41-47 1064-8887 39:1<41 1996 39 11182 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer