# Simulation of rotational spectra of a symmetric top

• luisgml_2000
In summary, the conversation discusses a query about simulating the rotational spectrum of a symmetric top. The speaker has been able to produce a stick spectrum, but the lines do not match the positions of the peaks and the intensities of the rotational lines need to be simulated. The book "Rotational Structure in the spectra of diatomic molecules" is mentioned but it concludes that the components of the electronic transition moment are needed, which the speaker does not have. They are aware of programs like PGopher but want to do the simulation themselves. The suggestion is made to use the Wigner Eckart theorem to calculate relative intensities.
luisgml_2000
Hello fellow physicists,

I have a query about a practical matter. I'm trying to simulate the rotational spectrum of a symmetric top and so far I've been able to produce a stick spectrum of it.

My first problem is that the lines do not exactly match the positions of the peaks but my biggest problem is that I need to simulate the intensities of the rotational lines. I've looked into Kovacs' "Rotational Structure in the spectra of diatomic molecules" as it contains a discussion of the topic but the conclusion of the book is that I need the components of the electronic transition moment; in the end, I need th wavefunction of my molecule and I don't know it. Something tells me that this is the wrong way to go.

I'm aware of programs like PGopher that could do the job but I need to do this thing myself for the sake of my project.

If you could help me out in this undertaking with a piece of advice or a useful reference I'd really appreciate it.

Thanks.

Of course you need the moment to calculate the absolute height of the lines but I think by using the Wigner Eckart theorem it should be possible to get all the relative intensities.

## 1. What is a symmetric top in rotational spectroscopy?

In rotational spectroscopy, a symmetric top refers to a molecule or atom that has a symmetric shape, such as a sphere or a cylinder. This symmetry allows for the rotational spectra to be simulated using simpler mathematical models.

## 2. Why is it important to simulate the rotational spectra of a symmetric top?

Simulating the rotational spectra of a symmetric top allows scientists to understand the rotational motion and energy levels of molecules and atoms. This information is crucial in fields such as chemistry, physics, and astronomy, where the behavior and properties of molecules and atoms play a significant role.

## 3. What factors are considered in the simulation of rotational spectra of a symmetric top?

The simulation of rotational spectra takes into account factors such as the molecular geometry, the moment of inertia, and the rotational energy levels of the molecule or atom. These factors are used to develop mathematical models that can accurately predict the spectral lines observed in experiments.

## 4. Is it possible to accurately simulate the rotational spectra of a symmetric top?

While the rotational spectra of a symmetric top can be accurately simulated using mathematical models, there are some limitations. These models assume ideal conditions and do not account for factors such as temperature, pressure, and interactions with other molecules. Therefore, there may be some discrepancies between simulated and experimental results.

## 5. How are the results of the simulation of rotational spectra of a symmetric top used in research?

The results of the simulation of rotational spectra of a symmetric top are used to analyze and interpret experimental data, as well as to make predictions about the behavior and properties of molecules and atoms. This information is essential in various research fields, including spectroscopy, quantum mechanics, and molecular physics.

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