微扰展开 (t) (t) O dt (1) W. iomnt(o) (+1) ()微扰展开 ( 1) ( ) (1) (0) (0) ( ) 0 ( ) ( )         n i t m n m n n i t m n m n m m m c W e c dt d i c W e c dt d i c dt d i c t c t m n m n    = = = = +   