Singular behavior of the density state called a van Hove singularity

In summary, the conversation discusses a condensed matter problem involving a phonon dispersion relation for a monatomic linear chain. The speaker was asked to derive an expression for the density state per unit length, which they obtained as g(\omega) = \frac{L}{a\p} \frac{1}{4C/M - \omega^{2}}. The conversation also mentions a singularity that occurs at \omega = 2(\frac{C}{M})^{1/2}, and the speaker asks for an explanation of its origin. The summary concludes with a question about how the singularity relates to the problem.
  • #1
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Homework Statement



I was doing a condensed matter problem (3rd year) of a phonon dispersion relation for a monatomic linear chain. It asked told me to derive an expression for the density state per unit length and I obtained the following:
[itex] g(\omega) = \frac{L}{a\p} \frac{1}{4C/M - \omega^{2}}[/itex]

Homework Equations



The singularity occurs at
[itex]\omega = 2(\frac{C}{M})^{1/2} [/itex]


The Attempt at a Solution


Can someone explain the origin of this singularity?
 
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  • #2
I understand that a singularity occurs when the denominator becomes zero and hence you get an infinite value for the corresponding function. But how does this relate to the problem?
 

1. What is a van Hove singularity?

A van Hove singularity is a type of singular behavior in the density of states (DOS) of a material at a specific energy level. It is characterized by a sharp peak or dip in the DOS curve, indicating a high density of electronic states at that energy level.

2. How is a van Hove singularity different from other singularities?

A van Hove singularity is distinct from other singularities, such as a Fermi singularity or a Mott singularity, because it occurs at a specific energy level rather than across a range of energies. It is also related to the electronic band structure of a material, whereas other singularities may be caused by interactions between particles.

3. What causes a van Hove singularity?

A van Hove singularity is caused by a change in the curvature of the electronic band structure of a material. This can occur due to changes in the crystal structure, the number of electrons in the system, or the presence of impurities or defects.

4. How do van Hove singularities impact the properties of materials?

Van Hove singularities can significantly affect the electronic and optical properties of materials. They can lead to enhanced conductivity, optical absorption, and excitonic effects. They also play a crucial role in phase transitions and collective phenomena in materials.

5. Can van Hove singularities be manipulated or controlled?

Yes, van Hove singularities can be manipulated or controlled through various methods, such as changing the composition or structure of a material, applying external stimuli, or using techniques like doping or strain engineering. This allows for the tuning of material properties and the development of new functional materials with desired characteristics.

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