r(J-21)2=1 01 01 r(1-2D)2=r( 00 2 01 7(J2-21 0 07 2 1 0 1 0 1 ( 2 ) ( 0 0 0 r J I r     − =         2 )=1， 2 2 0 1 0 ( 2 ) ( 0 1 0 r J I r     − =         2 )=0， 2  − = r J I ( 2 ) 1