Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help with canonical ensemble

  1. Nov 28, 2006 #1
    Hi there,

    I have a system with the following energy using the einstein model:

    [tex]E_\nu=\sum_{i=1}^{2N} h\omega n_i+\sum_{j=1}^{N} h\omega n_j[/tex]
    I need to set up a canonical ensemble for this.

    How would I write the partition function please?
  2. jcsd
  3. Nov 28, 2006 #2

    Dr Transport

    User Avatar
    Science Advisor
    Gold Member

    Isn't the partition function defined as

    [tex] \int \frac{d^{3N}p d^{3N}q}{N! h^{3N}} e^{-\beta H(p,q)} [/tex]

    for [tex] N [/tex] particles. You just need to substitute for the energy that you have and perform the integration (hint integrate over all the freuqncies [tex] \omega [/tex] and you should only have to do one and simplify).
  4. Nov 29, 2006 #3


    User Avatar
    Science Advisor
    Homework Helper

    First, it't [itex] \hbar [/itex] instead of "h" in E_{\nu}. Second, this looks like an application of quantum statistics, and so the classical partition function won't be of any use.

  5. Nov 30, 2006 #4
    Thanks, I think my problem is that I don't know how to set this up as thesummations have different upper values.

    I want to write something like:

    [tex]Q=\sum_{i=1}^{2N} e^{-\beta \hbar n_i}+\sum_{j=1}^N e^{-\beta \hbar n_j}[/tex]

    where Q is the partition function.

    Does this look anything like the partition function?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook