Equation Icon  ′ i [ (0) (0) ′] χOF (t − t ) =-- ˆO (t),Fˆ (t) , ℏ [ ] χFF (t − t′) = i ˆF(0)(t),Fˆ(0)(t′) , ℏ ′ i-[ (0) (0) ′] χxx (t − t ) = ℏ xˆ (t),xˆ (t) . (130 )