ABSTRACT
WemustreplaceHbyHeverywhere.Inparticular,wemodifythe Heisenbergrepresentation,replacingthedefinition(5-3)by
A(t)=eiiitAe-Uit(7-2)
308InteractingFermiSystems
Itiseasytogofromtherepresentation(7-2)totheusualHeisenbergrepresentation.Forexample,wehave
(7-3)
Inordertosimplifythenotation,wesuppressthebarsoverA,itbeing understoodthatHisnolongertheHamiltonianbutthefreeenergy(7-1).
