The Nature of the Cooper Pair - University of Liverpool

Recall that
So
Returning to
V kk ′ = V0
l = πve/ω D.
k − k ′ = ω D/ve.
� l
0 sin(kr) sin(k′ r)dr,
we can say that if k − k ′ is more than ω D/ve, the integral is
approximately zero.
If not, we may roughly take it to be the value when k = k ′ ,
which is l/2. Therefore
V kk ′ =
Superconductivity 39
�
lV0/2 for k − k ′ < ω D/ve
0 for k − k ′ > ω D/ve