open system variance of N
Posted by peeterjoot on March 16, 2013
Question: Variance of in open system ( pr 3.14)
Show that for an open system
In terms of the grand partition function, we find the (scaled) average number of particles
Our second derivative provides us a scaled variance
Together this gives us the desired result
 E.A. Jackson. Equilibrium statistical mechanics. Dover Pubns, 2000.