Dear muzi352 or whatever your name is,

Can you please tell us which code you use and what the input files are. Otherwise it is impossible to help

Matthias

On Mar 7, 2012, at 11:32 AM, muzi352 wrote:

Dear Matthias: I begin with the Hamiltonian for a chain with spins S=1/2 , <截图1.png> 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 Offdiagonal spin correlations[( 0 ) -- ( 3 )] -0.03664352593820266 Offdiagonal spin correlations[( 0 ) -- ( 4 )] 0.002203905249778245 Offdiagonal spin correlations[( 1 ) -- ( 3 )] 0.0331275686776057 Offdiagonal spin correlations[( 1 ) -- ( 4 )] -0.007827950318578362 Offdiagonal spin correlations[( 0 ) -- ( 4 )] -0.04668994676799755 Offdiagonal spin correlations[( 0 ) -- ( 5 )] 0.01338526650557481 Offdiagonal spin correlations[( 1 ) -- ( 4 )] 0.05418339350735944 Offdiagonal spin correlations[( 1 ) -- ( 5 )] -0.02572536103232437 Offdiagonal spin correlations[( 0 ) -- ( 5 )] 0 Offdiagonal spin correlations[( 0 ) -- ( 6 )] 0