# Fermi-Dirac Statistics

by tyco05
Tags: fermidirac, statistics
P: 161
Hey kids,

The question I'm having trouble with (this time) is as follows:

Show that the Fermi-Dirac distribution function,

$$f_{FD}(E)=\frac{1}{e^{(\frac{E-E_f}{kT})}+1}$$

Has the following functional form at T= 0K
(see attachment)

Now, the first thing that screamed at me was the division by T in the exponential bit. If T=0, what is going on!?

The obvious things are:

E>Ef then f(E) = 0

and

E<Ef then f(E) = 1.

I'm just really confused at how I can show that the function has that form at T=0K

Any ideas?

Cheers
Attached Images
 FD-distribution.bmp (15.3 KB, 18 views)
 HW Helper Sci Advisor P: 2,004 I don't understand your question. Didn't you just show the function has that form? $$\lim_{T \rightarrow 0}f_{FD}(E)=\left\{ \begin{array}{ll}1 & \mbox{if} EE_f$$
 P: 161 I'm glad somebody else doesn't understand the question either. They want me to 'show' that the distribution has the (attached pic) form at T=0. The real problem I'm having is how do I "show" that it has that form? Via two lines of maths? That's it?
HW Helper