scholarly journals Improved upper and lower energy bounds for antiferromagnetic Heisenberg spin systems

2003 ◽  
Vol 33 (3) ◽  
pp. 285-292 ◽  
Author(s):  
K. B�rwinkel ◽  
H.-J. Schmidt ◽  
J. Schnack
2002 ◽  
Vol 35 (31) ◽  
pp. 6545-6555 ◽  
Author(s):  
Heinz-J$uuml$rgen Schmidt

2019 ◽  
Vol 31 (9) ◽  
pp. 095802 ◽  
Author(s):  
J D Alzate-Cardona ◽  
D Sabogal-Suárez ◽  
R F L Evans ◽  
E Restrepo-Parra

2013 ◽  
Vol 27 (16) ◽  
pp. 1350064 ◽  
Author(s):  
HEINZ-JÜRGEN SCHMIDT

We consider the Heisenberg spin triangle with general coupling coefficients and general spin quantum number s. The corresponding classical system is completely integrable. In the quantum case the eigenvalue problem can be reduced to that of tridiagonal matrices in at most 2s+1 dimensions. The corresponding energy spectrum exhibits what we will call spectral symmetries due to the underlying permutational symmetry of the considered class of Hamiltonians. As an application we explicitly calculate six classes of universal polynomials that occur in the high temperature expansion of spin triangles and more general spin systems.


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