Calculating Entropy of 2D Free Particles: Statistical Physics Challenge

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Discussion Overview

The discussion revolves around calculating the entropy of a large number of free particles in a two-dimensional box, specifically using the definition of entropy from statistical mechanics. Participants explore the implications of having a continuum of states and the appropriate statistical ensemble to apply, considering factors like temperature and volume.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Homework-related

Main Points Raised

  • One participant questions how to calculate entropy for a continuum of states given the definition S=-k(sum on r: pr*ln(pr)).
  • Another suggests using the quantum canonical ensemble and computing the partition function to find the entropy, while expressing uncertainty about the temperature's role.
  • A participant expresses confusion about the terminology, particularly regarding the partition function, indicating a lack of familiarity with some concepts in statistical mechanics.
  • Concerns are raised about the problem's lack of information regarding the volume of the box and temperature, leading to a suggestion that the microcanonical ensemble might be more appropriate.
  • One participant inquires about the density of states, indicating a need for further clarification on the concepts involved.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the appropriate approach to take, with multiple competing views on the statistical ensembles and the implications of missing information.

Contextual Notes

The discussion highlights limitations due to missing assumptions about temperature and volume, as well as unresolved questions regarding the eigenvalues of the density operator.

Palindrom
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Hi all.

So something's bothering me;

Given the def. S=-k(sum on r: pr*ln(pr)) for the entropy, find the entropy of N>>1 free particles moving in a 2d box with energy E.

Now, don't I have a continuum of states here? How do I do that?

Thanks :smile:
 
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Use the quantum canonical ensemble...Compute the partition function and then the entropy.

Doesn't mention anything about the temp...Could it be the microcanonical ensemble...?:confused:

Daniel.
 
Hum... you've kinda just given me a dizzy head... :smile:

It's only my second week of statistical mechanics, so consider that.

And... I might not recognize some of the terms in English. What's a partition function?

Sorry :rolleyes:
 
The problem is weird,as it doesn't mention about the volume of the box,nor the temperature.That would mean the microcanonical ensemble,but again i can't see a way to compute the eigenvalues of the density operator.

Daniel.
 
What density? Of states?
Weird anyway... I'll keep thinking about it.
 

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