Why Is Entropy Non-Zero in This Hamiltonian System?

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SUMMARY

The discussion focuses on demonstrating why entropy is non-zero in a Hamiltonian system, specifically using the Ising model. Participants suggest utilizing the partition function Z to derive the entropy S, defined by the equation S = ∂_T (k_B T ln Z). Additionally, the relationship S = k_B ln Ω(T, H) is highlighted, where Ω(T, H) represents the number of states at temperature T and magnetic field H. These equations are essential for understanding the thermodynamic properties of the system.

PREREQUISITES
  • Understanding of Hamiltonian mechanics
  • Familiarity with statistical mechanics concepts
  • Knowledge of the Ising model and its partition function
  • Basic thermodynamic principles, including entropy and temperature
NEXT STEPS
  • Study the derivation of the Ising model's partition function Z
  • Explore the relationship between entropy and the number of microstates Ω(T, H)
  • Investigate the implications of non-zero entropy in Hamiltonian systems
  • Learn about advanced statistical mechanics techniques for calculating thermodynamic properties
USEFUL FOR

This discussion is beneficial for physics students, researchers in statistical mechanics, and anyone interested in the thermodynamic behavior of Hamiltonian systems.

romeo31415
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Homework Statement


Bonjour,

Given the hamiltonian

image.png

Show that
image.png

The Attempt at a Solution


image.png
[/B]

https://mail.google.com/mail/u/0/?ui=2&ik=926d313718&view=fimg&th=14b1676f1c775525&attid=0.4&disp=emb&realattid=ii_14b16759c66f2c07&attbid=ANGjdJ8nHkVansCbZY79hWetamch9gX2IeJFX1IdCsZvvCq0wrrFx61OU_3uTU3s5BodY--fZWORr1KruMhwcc1mUUynX4vyaIqg7Pee2njVuAEpG5rRFC7jNJ4cxBE&sz=w874-h108&ats=1422015353399&rm=14b1676f1c775525&zw&atsh=1

I cannot explain why S=0
 

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One thing you may be able do for is use the exact solution for the partition function ##Z## of the Ising chain.
##S = \partial_T k_B T \ln Z##

In other situations like this one may be able to start by using ##S = k_B \ln \Omega(T, H) ##, where ##\Omega(T, H) ## is the number of states corresponding to T and H.
 
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