- #1
mupsi
- 32
- 1
The derivative of the Green's function is:
[tex]
i \dfrac{dG_{A,B}(t)}{dt} =\delta(t) \left< {[A,B]}\right>+G_{[A,H],B}(t)
[/tex]
the Fourier transform is:
[tex]
\omega G_{A,B}(t)=\left< {[A,B]}\right>+G_{[A,H],B}(\omega)
[/tex]
but this would require that the Green's function is 0 for t->inf. Why is that the case? It is clear that it must vanish at t->-inf because of the heaviside function but not at inf.
[tex]
i \dfrac{dG_{A,B}(t)}{dt} =\delta(t) \left< {[A,B]}\right>+G_{[A,H],B}(t)
[/tex]
the Fourier transform is:
[tex]
\omega G_{A,B}(t)=\left< {[A,B]}\right>+G_{[A,H],B}(\omega)
[/tex]
but this would require that the Green's function is 0 for t->inf. Why is that the case? It is clear that it must vanish at t->-inf because of the heaviside function but not at inf.