Undergrad Do Simple 2D Ising Models Have Constant Density of States?

Click For Summary
SUMMARY

The discussion centers on the calculation of the density of states (DOS) in simple 2D Ising models and its implications for using the Boltzmann factor in statistical mechanics. Participants explore the relationship between energy, temperature, and the density of states, specifically questioning how to derive a DOS expression that excludes mass while incorporating constants like kB and T. The conversation highlights the need for clarity in the derivation of DOS expressions, particularly in relation to the Maxwell-Boltzmann energy distribution.

PREREQUISITES
  • Understanding of the Ising model in statistical mechanics
  • Familiarity with the Boltzmann factor and its applications
  • Knowledge of Maxwell-Boltzmann statistics and energy distributions
  • Basic concepts of density of states in quantum mechanics
NEXT STEPS
  • Research the derivation of density of states for the ideal gas model
  • Explore the relationship between energy, temperature, and the Boltzmann factor
  • Study the implications of the Ising model on phase transitions
  • Investigate algorithms used for calculating density of states in statistical mechanics
USEFUL FOR

Physicists, researchers in statistical mechanics, and students studying thermodynamics who are interested in the properties of the Ising model and density of states calculations.

rabbed
Messages
241
Reaction score
3
Do simple 2D Ising models have constant density of states?
How is it calculated?
 
Science news on Phys.org
What research have you done so far on this? What have you found out?
 
I just learned about density of states and the Boltzmann factor.
If the density of states does not depend on the energy/is constant, we can just use the Boltzmann factor to calculate the probability of a particle being in a state of certain energy. And with the Ising model only the BF is used, right?
I googled and found some people finding the DOS using some algorithm, but no calculations or justifications for why it would be constant.
Pretty new to the Ising model also, just thought the DOS would be a fundamental thing to know when deriving it
 
Okay, I found an explanation for the Ising model..

Next question - The MB energy distribution is: MB_PDF(E) = 2*sqrt(E/pi) * 1/(kB*T)^(3/2) * e^(-E/(kB*T))
How do I arrive at the density of states which hides inside the expression 2*sqrt(E/pi) * 1/(kB*T)^(3/2) ?
I've only seen DOS that have "h" in them.. I want it to contain only E, pi, kB and T..
This is how far I've gotten (using a momentum vector):
V = 4*pi*p^3/3
dV = 4*pi*p^2*dp
dV = 4*pi*(2*m*E)*sqrt(m/(2*E))*dE (since p = sqrt(2*m*E) and dp = sqrt(m/(2*E))*dE)
dV = 2*pi*(2*m)^(3/2)*sqrt(E)*dE

How do I get rid of the m and how do I get in kB and T?
 
Last edited:
Since no one cares, I might as well ask Another question:
Is there a DOS-expression D for the ideal gas which will both fit into MB_PDF(E, T) = D * e^(-E/(kB*T)) / Z (where Z normalizes the distribution)
as well as giving an extensive entropy S = kB*ln(D) ?
It should be the same quantity, right?
 
rabbed said:
Since no one cares, I might as well ask Another question:
Is there a DOS-expression D for the ideal gas which will both fit into MB_PDF(E, T) = D * e^(-E/(kB*T)) / Z (where Z normalizes the distribution)
as well as giving an extensive entropy S = kB*ln(D) ?
It should be the same quantity, right?
Sorry to see you're not getting any help, but starting a new question in the same thread is a VERY bad idea. I'd suggest that you delete it here and start a new thread.
 

Similar threads

  • · Replies 0 ·
Replies
0
Views
872
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 0 ·
Replies
0
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 0 ·
Replies
0
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
3
Views
2K