Classical free electron theory could not explain many physical properties. This drawbacks of classical theory can be rectified using quantum theory.
The failures of classical theories were removed by Sommerfield in 1928. He developed a new theory applying quantum mechanical concepts and Fermi-Dirac statistics to the free electrons in the metal. This theory is called quantum free electron theory.
Classical free electron theory permits all electrons to gain energy. But quantum free electron theory permits only a fraction of electrons to gain energy. This theory was proposed by making slight modification in the classical free electrons theory and by retaining most of the postulates of the classical free electron theory.
Advantages of Quantum Free Electron Theory
- It explains the specific heat capacity of materials.
- It explains compton effect, photoelectric effect.
- It gives the correct mathematical expression for the thermal conductivity of metals.
- It explains the superconducting property.
Disadvantages of Quantum Free Electron Theory
- This theory fails to explain the positive value of Hall coefficients.
- This theory fails to distinguish between the metal, semiconductor and insulator.
| Read More Topics |
| Electrical conductivity (σ) |
| Success of classical free electron theory |
| Classical free electron theory of metals |
