Fermi-Dirac and Bose-Einstein Distributions in Quantum Gas: Comparison and Application, Study notes of Statistics

An overview of Fermi-Dirac and Bose-Einstein distributions in the context of quantum gas. It discusses the relation between these distributions and the Boltzmann distribution, the application of Fermi-Dirac distribution in modelling conduction electrons in metals, and the concept of degenerate Fermi gas. The document also includes formulas for calculating occupancy using Boltzmann distribution and wavefunctions for free electrons in a metal block.

Typology: Study notes

2021/2022

Uploaded on 09/27/2022

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Review
For cases when Z
1
>> Ncondition is not met:
Fermi-Dirac Distribution (fermions)
Bose-Einstein Distribution (bosons)
n
FD
=1
e
(
ε
μ
)/kT
+1
n
BE
= 1
e
(
ε
μ
)/kT
1
Fermi-Dirac Distribution
Consider cases looking at
ε
and
μ
n
FD
=1
e
(
ε
μ
)/kT
+1
pf3
pf4
pf5

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Review

condition is not met: N >>^1 Z For cases when Fermi-Dirac Distribution (fermions) • Bose-Einstein Distribution (bosons) •

=^ FD n

e

kT )/ μ ε −(

=^ BE n

e

kT μ)/ε −(

Fermi-Dirac Distribution

μ and ε Consider cases looking at •

=^ FD n

e

kT )/ μ ε −(

Fermi-Dirac Distribution

μ and ε Consider cases looking at •

Relation to Boltzmann Distribution

) s ( NP =^ Boltzmannn Calculate occupancy •

Application of Fermi-Dirac Distribution

Modelling behavior of conduction electrons in metal •

  • Gas of fermions at very low temperature Condition for Boltzmann statistics is not met •
V
N

Q υ <<

At Zero Temperature

=0, Fermi-Dirac distribution becomes step function T At • =0) T (μ≡^ F ε – are occupied and those above^ F ε When nearly all states below • are empty

  • Called degenerate gas depends on total number of electrons in system^ F ε •

Degenerate Fermi Gas

Electrons in the system are free particles •

  • Ignoring attractive forces from ions in the crystal lattice Wavefunctions for free electron in metal block •
  • Represented by standing wave modes =^ n λ L 2 n =^ np ; h n λ = hn
L 2