Maxwell-Boltzmann distribution for transport equations

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SUMMARY

The discussion focuses on calculating transport coefficients using the Maxwell-Boltzmann (MB) distribution for transport equations. The integral for electrical conductivity is derived from the MB distribution function, specifically using the formula for normalized MB distribution. The user seeks clarification on determining the normalization constant C and the relationship between the mean number density and the total number of particles. The final goal is to arrive at Drude's formula for electrical conductivity, σ = (n e² τ) / m.

PREREQUISITES
  • Understanding of Maxwell-Boltzmann distribution and its applications
  • Familiarity with transport coefficients in statistical mechanics
  • Knowledge of electrical conductivity and Drude's model
  • Basic calculus, particularly integration techniques for solving transport equations
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  • Research the derivation of the Maxwell-Boltzmann distribution function
  • Study the normalization of probability distributions in statistical mechanics
  • Learn about the relationship between mean number density and total particle number in thermodynamics
  • Explore advanced topics in transport phenomena and their mathematical formulations
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Physicists, engineers, and students studying statistical mechanics, particularly those interested in transport phenomena and electrical conductivity calculations.

Denver Dang
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I have to calculate the transport coefficients for the Maxwell-Boltzmann distribution. But I'm not sure what distribution I have to use.
As far as I know it should not be the MB distribution for v-space (Velocity) or E-axis (Energy), since that will get me the wrong dimensions in the end. I have to use the distribution per state.

But I'm not sure how this looks. The integral I have to solve, for me getting the electrical conductivity (1st transport coefficient) I need, is given by:

{{\mathcal{L}}^{\,\left( 0 \right)}}={{\left( \frac{2m}{{{\hbar }^{2}}} \right)}^{3/2}}\frac{{{e}^{2}}\tau }{{{\pi }^{2}}m}\int{\left( -\frac{\partial {{f}_{MB}}}{\partial \varepsilon } \right)}\,{{\varepsilon }^{3/2}}d\varepsilon,

at least, again, when trying to calculate the electrical conductivity, which in the end should end up being Drudes formula \sigma =\frac{n{{e}^{2}}\tau }{m}.

So basically, not hard. But I have to get the distribution function right.

As far as I know the MB-distribution is given by:

{{f}_{MB}}\left( \varepsilon \right)=C{{e}^{-\varepsilon /{{k}_{B}}T}},

where C is what I need to figure out, since that will determine the dimensions of my coefficients.

According to my book the normalized MB distribution function is:

\bar{n}=\frac{{\bar{N}}}{{{Z}_{1}}\left( T,V \right)}{{e}^{-\varepsilon /{{k}_{B}}T}},

where:

\frac{{{Z}_{1}}\left( T,V \right)}{{\bar{N}}}=\frac{V}{{\bar{N}}}\left( \frac{2\pi m{{k}_{B}}T}{{{h}^{2}}} \right){{Z}_{\operatorname{int}}}\left( T \right),

and {{Z}_{\operatorname{int}}}\left( T \right) = 1 in my case.

But I'm not quite sure how to about this? As far as I can see, it's not just inserting the reversed term of this in C - at least not from what I can see. Maybe it's the V/N I'm not sure about.

So, anyone who can give me a clue, or...?
 
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Your normalization factor should be :

\frac{{{Z}_{1}}\left( T,V \right)}{{\bar{N}}}=\frac{V}{{\bar{N}}}\left( \frac{2\pi m{{k}_{B}}T}{{{h}^{2}}} \right)^{3/2}


The n in the drude law is the number density. i.e. the number of electrons per unit volume. In your normalization constant what is \bar{n}, \bar{N} ? :wink:
 
The bar over n and N means the "mean" of whatever it is...

But do I know what this is ?
Or at least V/N, or...?
 

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