Spring 2006 PHY 203: Introduction to Statistical Mechanics Assignment #7 Due at the beginning of class on Wednesday, 3/29/06 Problems: 1. Deduce the virial expansion ∞ X PV = al nkT l=1 λ3 v !l−1 using the expressions: 1 P = 3 g5/2 (z) kT λ and N − N0 1 = 3 g3/2 (z) V λ with λ the thermal wavelength and g(z) the Bose Einstein functions. Verify the quoted values of the virial coefficients – it is sufficient to find the first three terms, a1 , a2 , and a3 . [30 points] 2. Consider an ideal Bose gas in the grand canonical ensemble and study fluctuations in the total number of particles N and total energy E. Discuss, in particular, the situation when the gas becomes highly degenrate. Use the following definitions: ∂hN i ∂µ 2 h(N − hN i) i = kT 2 h(E − hEi) i = kT [20 points] 1 2 ∂U ∂T ! ≡ (∆N )2 T,V ! ≡ (∆E)2 z,V