Where did the extra 8 come from in the derivation for density of states?

In summary, the conversation revolved around a derivation for the density of states, with one person finding a different result on a webpage compared to a book. They discuss the use of factors such as pi and hbar, with one person realizing their mistake in their calculations. The extra 8 in the book's result comes from the use of hbar.
  • #1
iampaul
93
0
TL;DR Summary
I tried to follow the derivation, but I got a different result
I was looking for a derivation for the density of states and I came across this page: https://ecee.colorado.edu/~bart/book/book/chapter2/ch2_4.htm

I followed the derivation and came up with:
g(E) = (1/L3)dN/dE
= (1/L3)L3/2*k2 * dk/dE
=K2/2 * dk/dE
=K2/2 *
g(E) = (∏√2/h3)*m3/2*√2but the book gives:
g(E) = (8∏√2/h3)*m3/2*√2

where did the extra 8 come from?
 
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  • #2
Check your math. You miss some factors ##\pi##.
The 8 comes from the ##\ \hbar^3\ ## and ##\ \hbar = {h\over2\pi}##
 
  • #3
BvU said:
Check your math. You miss some factors ##\pi##.
The 8 comes from the ##\ \hbar^3\ ## and ##\ \hbar = {h\over2\pi}##
Thanks, I've been plugging in ##\ \hbar = {h\over\pi}##.
 

1. What is the concept of density of states?

The density of states is a measure of the number of available quantum states per unit energy in a given system. It describes the distribution of energy levels in a material or system, and is an important factor in understanding the electronic and thermal properties of materials.

2. How is the density of states derived?

The density of states can be derived from the energy eigenvalues of a system, which are determined by solving the Schrödinger equation. It can also be calculated using statistical mechanics methods, such as the Maxwell-Boltzmann distribution.

3. What is the significance of the density of states in materials science?

The density of states is a crucial parameter in understanding the electronic and thermal properties of materials. It helps to explain phenomena such as electrical conductivity, thermal conductivity, and specific heat capacity.

4. How does the density of states vary with temperature?

The density of states is typically dependent on temperature, as it is related to the energy levels of a system. At higher temperatures, more energy levels become available, leading to an increase in the density of states.

5. Can the density of states be experimentally measured?

Yes, the density of states can be measured using various techniques, such as spectroscopy or tunneling microscopy. These methods allow for the determination of the energy levels and their distribution in a material, which can then be used to calculate the density of states.

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