- #1
hokhani
- 488
- 8
How to calculate [itex]<n_i ^2>[/itex] for an ideal gas by the grand partition function ([itex]<n_i>[/itex] is the occupation number)? In other words, I like to know how do we get to the formula [itex]<n_i>=-1/\beta (\frac{\partial q}{\partial\epsilon})[/itex] and [itex]<n_i ^2>=1/Z_G [-(1/\beta \frac{\partial }{\partial\epsilon})^2 Z_G][/itex]?
[itex]Z_G[/itex] is grand partition function , q=[itex]ln Z_G[/itex] and [itex]\epsilon[/itex] is the energy of the corresponding level.
[itex]Z_G[/itex] is grand partition function , q=[itex]ln Z_G[/itex] and [itex]\epsilon[/itex] is the energy of the corresponding level.