Differential equation similar to Legendre

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The discussion centers on solving a complex differential equation related to angular momentum, featuring terms that complicate separability. The equation includes a combination of sine and cosine functions, prompting the consideration of spherical harmonics, specifically the linear combination of Legendre polynomials. Participants suggest applying the angular momentum operator to spherical harmonics with arbitrary values to explore potential solutions. There is a focus on leveraging the properties of these polynomials to simplify the equation and identify functions that could satisfy it. Overall, the conversation emphasizes the challenge of finding a solution while exploring various mathematical approaches.
Physicslad78
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I am trying to solve the following differential equation:

<br /> (\frac{L^2}{6k^2}+\frac{w\sqrt{3}}{2}\sin^2\theta\cos 2\phi)\psi=E\psi<br />

where L^2is the angular momentum given by:
\frac{1}{\sin\theta}\frac{\partial}{\partial\theta}(sin\theta\frac{partial}{\partial\theta})-\frac{1]{sin^2\theta}\frac{\partial^2}{\partial\phi^2}<br />. \theta goes from 0 to \pi while \phi goes from 0 to 2 \pi. k and w are constants and E is the energy of the system.. This differential equation seems non separable. Any ideas how to solve it...I also realized that the term sin^2\theta\cos 2\phi is a combination of (Y_{2,-2]+ Y_{2,2}). But then how to continue?

Thanks
 
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Sorry L^2 is:
<br /> \frac{1}{\sin\theta}\frac{\partial}{\partial\theta} (\sin\theta\frac{partial}{\partial\theta})-\frac{1]{\sin^2\theta}\frac{\partial^2}{\partial\phi^2}<br /> <br />
 
You mean

L^2 = \frac{1}{\sin\theta}\frac{\partial}{\partial\theta}\left(\sin\theta\frac{\partial}{\partial\theta}\right)-\frac{1}{\sin^2\theta}\frac{\partial^2}{\partial\phi^2}.

Some ideas: apply the operator to Y_L^M with arbitary values of L,\,M and see if you can determine L,\,M using the properties of the polynomials, or maybe using a linear combination of Legendre polynomials, or appliyng the operator to f(\theta)Y_L^M,\,g(\phi)Y_L^M,\,h(\theta,\phi)Y_L^M and use the properties of the polynomials to simplify the equation and determine f,\,g,\,h.

Just ideas.
 
Last edited:

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