Dear Matthias: I begin with the Hamiltonian for a chain with spins S=1/2 ,
use periodic boundary conditions ,the total number of sites is N=20. calculate correlation : Offdiagonal spin correlations has problem, why 0-0 and 0-1 offdiagonal spin correlations value is 0 ??
| Offdiagonal spin correlations[( 0 ) -- ( 0 )] | 0 | | Offdiagonal spin correlations[( 0 ) -- ( 1 )] | 0 | | Offdiagonal spin correlations[( 1 ) -- ( 0 )] | 0.2499999999999999 | | Offdiagonal spin correlations[( 1 ) -- ( 1 )] | 0.01195256946918583 | | Offdiagonal spin correlations[( 0 ) -- ( 1 )] | -0.1410917216909388 | | Offdiagonal spin correlations[( 0 ) -- ( 2 )] | -0.02578705926914329 | | Offdiagonal spin correlations[( 1 ) -- ( 1 )] | 0.05437436640436828 | | Offdiagonal spin correlations[( 1 ) -- ( 2 )] | 0.01374443422199295 | | Offdiagonal spin correlations[( 0 ) -- ( 2 )] | -0.04722700778251831 | | Offdiagonal spin correlations[( 0 ) -- ( 3 )] | -0.01673969792911871 | | Offdiagonal spin correlations[( 1 ) -- ( 2 )] | 0.06699300813943075 | | Offdiagonal spin correlations[( 1 ) -- ( 3 )] | 0.002194337470049455 |
