# Homework Help: Partition Function?

1. Jul 28, 2011

### greenfly

In my statistical physics class the partition function Z is used in the calculation of probabilities, and I even have a formula for it: Z=$\sum$e-E/kT. While this is all very good I am having some trouble actually grasping what it is, qualitatively speaking. Would someone please be able to explain it to me? I've tried google-ing, and firstly it pointed me to this site, but I've also followed a couple of other links that don't make much sense to me...

Cheers.

2. Jul 28, 2011

### Modulated

I'm afraid there's no simple answer to your question. As you will have seen, the partition function is just the denominator when you calculate the probability of observing a particular state; in other words, it's the sum of the probabilities of any state the system could possibly be in. The reason it's useful is that, if we know this sum, and in particular how it changes with temperature, we can actually deduce rather a lot about the system, and calculate any thermodynamic property we please—so it's a way of neatly rolling up a the crucial features of a system's thermodynamics into a single function.

Not sure how useful this will be to you but hope it helps!

3. Jul 29, 2011

### greenfly

Thank you! :)

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