1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Interpreting the Greens function in frequency space

  1. Dec 9, 2013 #1
    I have done a problem with a spin two electron spin system. I have found the Greens function propagator for spin up->spin up, which I have written in a form where the occupancy of spin up electrons is incorparated (attached) and from there I can get the spectral function, which will then be something like (omitting some factors):
    A=(1-N_up)δ(ω-E-U) + N_upδ(ω-E)
    But I am not sure how to interpret it. I know that for free electrons the spectral function A(k,ω) is something about how we can add an electron with momentum k to the system only by adding an electron with energy ω=E. But this can't be translated directly to how we can add an electron with spin up to the system since that would be impossible for 2 of the possible 4 configurations due to pauli exclusion. I can see that if the there is one electron of spin up the spectral function yields ω=E while if there is 0 ω=E+U. But how exactly is it to be interpreted?

    Attached Files:

  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted