Bose Equilibrium Distribution and Atomic Units

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Homework Help Overview

The discussion revolves around computing the average number of photons using the Bose-Einstein distribution in the context of atomic units. The original poster is attempting to express the average number of photons, denoted as ##\bar{n}##, while considering the implications of setting ##\bar{h} = 1## in their calculations.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore how to correctly express the average number of photons in atomic units, questioning whether the dimensionality of the exponential argument is consistent. There is also a discussion about the appropriate treatment of the Boltzmann constant and temperature in this context.

Discussion Status

Some participants have provided guidance on expressing quantities in atomic units and clarified the treatment of temperature and the Boltzmann constant. Multiple interpretations regarding the dimensionality of the exponential argument and the definition of the Boltzmann constant are being explored.

Contextual Notes

There is a note that temperature will remain in kelvins, despite the use of atomic units for other quantities. Additionally, the definition of the Boltzmann constant is under discussion, with references to external sources for clarification.

Raptor112
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Homework Statement


For my project I need to compute the average the number of photons given by the expression:
##\bar{n}= \frac{e^{-\bar{h}\omega/\kappa T}}{1-e^{-\bar{h} \omega / \kappa T}}##
where ##\kappa## is the Boltzmann constant and ##\omega## is the oscillator frequency. For the Hamiltonian in my project simulation, ##\bar{h} =1## so how would ##\bar{n}## be expressed?

Homework Equations


Is it as simple as ##\bar{h} =1## in the expression of ##\bar{n}## so:

##\bar{n}= \frac{e^{-\omega/\kappa T}}{1-e^{\omega / \kappa T}}##

but then doesn't the argument of the exponential has dimensions, as opposed to being dimensionless which is what it's supposed to be?
 
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You have to express all quantities in atomic units. For instance, ω will be in units of the inverse of the atomic unit of time. There is no atomic unit of temperature, so T will still be in kelvin, but you have to calculate the correct value for the Boltzmann constant.
 
Last edited:
DrClaude said:
You have to express all quantities in atomic units. For instance, ω will be in units of the inverse of the atomic unit of time. There is no atomic unit of temperature, so T will still be in kelvin, but you have to calculate the correct value for the Boltzmann constant.
According to wikipedia it's just one by definition:

https://en.wikipedia.org/wiki/Boltzmann_constant
 

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