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We have *both* energy *E* and the number of particles *N*
vary!

The same considerations as for canonical ensemble (substitute *N* for
*E*).

Probability of a state:

Here

is calledAnother formula:

so Yet another formula: sinceAverages:

-potential (compare to free energy *A*!)

Average entropy:

Or:

(1) |

**Consequence:**- -potential is just the product of volume and pressure:
**Proof:**- In thermodynamic limit Therefore Then and from (1)

© 1997

Tue Sep 9 22:39:08 EDT 1997