Density of modes graph from phonon dispersion graph

In summary, the conversation discusses the process of creating a density of modes graph based on a given phonon dispersion graph for NiAl. The individual is seeking guidance on how to approach this task and someone with limited knowledge of the subject suggests that the density is higher in areas where the gradient is lower, resulting in peaks at specific frequencies on the graph.
  • #1
PhysicsGirl90
17
0
While practicing for an upcoming exam, i ran into this question that has truly got me stumped. A phonon dispersion graph is given for NiAl (attached), and then they ask you to schematicaly plot the density of modes graph. I have the result of what is should look like, but i do not understand how to get from A to B.

Can someone point me in the right direction as to how i should go about doing this?
 

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  • #2
I know nothing of this subject, but from the 'density' term and just looking at the graphs here's my guess.
The density is high for the frequencies where the provided graphs 'spend' a lot of time. This is where the gradient is low. So you get very high peaks in density at 4 (lower middle graph) up to 5.75 (all three lower graphs) and 8-10.5 (upper graphs).
 

What is a density of modes graph?

A density of modes graph is a graphical representation of the number of normal modes of vibration in a material at different frequencies. It is typically derived from a phonon dispersion graph, which shows the relationship between phonon energy and wave vector.

How is a density of modes graph related to a phonon dispersion graph?

A density of modes graph is derived from a phonon dispersion graph. It is a plot of the number of phonon modes at each frequency, calculated by integrating the phonon dispersion curve over a frequency range.

What information can be obtained from a density of modes graph?

A density of modes graph provides information about the distribution of phonon modes in a material. It can also reveal the types of phonon modes present, as well as any gaps or discontinuities in the phonon dispersion curve.

How does the density of modes affect the thermal and mechanical properties of a material?

The density of modes is directly related to the heat capacity and thermal conductivity of a material. It also affects how heat and sound are transmitted through the material, as well as its mechanical properties such as stiffness and damping.

Why is the density of modes important in materials science?

The density of modes is an important concept in materials science as it helps us understand the thermal and mechanical properties of materials. It also plays a crucial role in the design and development of new materials with desired properties for various applications.

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