Wave in phonon as "forward and backward" movement vs temperature

In summary, classical physics can't describe the movement of a molecule due to the three body problem and vibration. However, vibrating light harvesting antennas may be able to take advantage of that movement by influencing the chaotic movement of temperature and the electrons.
  • #1
C Roth
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TL;DR Summary
How can we understand chaotic movement and temperature in a phonon? How is it affected by the waves of the phonon?
My first question here, so maybe not adequate or in the wrong topic, excuse me. I try to understand vibrating light harvesting antenna in biochemistry but it is a question of physics. We talk about a molecule with an emission spectra peak of about 650 nm.

In classical physics electrostatic and electrodynamic forces would let the electrons of a given molecule interact with each other in a rapid "for- and backward" movement in that molecule. That movement of the molecule may be more difficult to describe, but for the sake of discussion we stay with a likely constant linear extension and contraction of a chain like molecule, agitated by light. Because of the three (and more) body problem we are not able to predict those movements of the electrons, we just know that there is interaction, because of repulsion and the electric and magnetic fields created by the moving and spinning charges.

Now imagine the molecule as a wave (phonon). Isn't its rapid movement agitated by light influencing the chaotic movement of temperature and the electrons? The movements of the electrons could be seen as waves which interfere and resonate with the basic frequency of the phonon (molecule) and its multiples as in the Kuramoto model, couldn't it? So they would constantly get slightly redirected depending on their actual interfering or resonating waveform. Therefore couldn't it change the Boltzmann factor which depends on the temperature (as a measure for a probability distribution)?

Thank You
 
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  • #2
This appears to be an attempt to apply classical models to a molecule, which is inherently quantum mechanical.
 
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Thanks for your statement. Can you please give me a hint on what is wrong. It is just an attempt to think in two different concepts parallel. I didn't want to mix them. Chemistry is full of cases of classic models applied to a molecule, since computing power is still limited and costly, isn't it?
 
  • #4
Indeed, there are many things about molecules that can be modeled reasonably using a classical approach. But those models are usually based on abstractions, the most common being a molecular bond represented as a spring. The electrons in a molecule are very quantum mechanical, so you cannot consider a classical model for a molecule where electrons are still present.
 
  • #5
Thank you for your explanation. I see your point and I agree with you. Let me please try to explain my thought in a different way: There are different theories/concepts with different abilities and limits. Classical physics work well for observable objects which are not very small. Quantum mechanics work very well for very small objects, but it is not easy to use them for complex molecules and varying temperature and vibration states, because the distribution is a basic assumption and the temperature an important component of the Boltzmann factor. I wonder if nature is able to fulfill conditions which we don't consider, because we exclude them by the decision we make, when we choose our concept. The Kuramoto model could be a hint to that. What if nature knew processes which change from Fermi Dirac distribution to Bose Einstein distribution (maybe just for one atom) by altering "temperature" close to zero by superposition of waves (Kuramoto model)? Would we be able to describe that quantum mechanically? Certainly chemists would never consider an atom behave like a boson because of the Pauli exclusion principle. Therefor it would stay hidden. But nevertheless it is thinkable, isn't it?
Gratefully C
 

Related to Wave in phonon as "forward and backward" movement vs temperature

1. What is a phonon?

A phonon is a quantum of vibrational energy or a unit of vibrational energy in a crystal lattice. It can be thought of as a particle-like representation of a sound wave.

2. How does temperature affect the movement of phonons?

At higher temperatures, phonons have more energy and therefore move faster. This results in an increase in the amplitude and frequency of their vibrations, leading to a higher rate of forward and backward movement.

3. What is meant by "forward and backward" movement of phonons?

In a crystal lattice, phonons can move in two directions - forward and backward. This movement is a result of the oscillation of atoms within the lattice. As phonons move, they transfer energy and momentum, which affects the thermal and mechanical properties of the material.

4. How does the "forward and backward" movement of phonons impact thermal conductivity?

The movement of phonons in a material affects its thermal conductivity. As phonons move, they transfer energy and momentum, which can either enhance or hinder the flow of heat through the material. This is why materials with higher phonon movement, such as metals, have higher thermal conductivity compared to materials with lower phonon movement, such as insulators.

5. Can the "forward and backward" movement of phonons be controlled?

Yes, the movement of phonons can be controlled through various methods such as altering the crystal structure of the material or introducing impurities. This can be useful in engineering materials with specific thermal and mechanical properties for various applications.

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