What Is the Solution to Associated Legendre Polynomials for m=1 and l=1?

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SUMMARY

The solution to the Associated Legendre Polynomials for m=1 and l=1 is derived as Sqrt(3/8π) e^((+/-)iφ) * sin(θ). The calculation involves substituting x = cos(θ) into the polynomial formula, specifically P^{1}_{1}={(-1)^1 \over 2 \cdot 1!} (1-x^2)^{1/2} \cdot {d^2 \over dx^2}(x^2-1). A common error in this process is neglecting the application of both l and m values, leading to incorrect simplifications. The discussion emphasizes the importance of careful substitution and differentiation in obtaining the correct result.

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  • Understanding of Associated Legendre Polynomials
  • Knowledge of trigonometric identities, specifically sin(θ) and cos(θ)
  • Familiarity with differentiation techniques in calculus
  • Basic grasp of complex numbers and exponential functions
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9def74632e12c73e7638541a31d51fca.png


m=1 and l=1

x = cos(θ)

What would be the solution to this?

Thanks.
 
Last edited:
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We won't do the calculation for you. Why can't you do it yourself? What part of it doesn't make sense to you?
 
I've tried a lot of things, but I don't get it. (NOT a physics/math student)

I get this:

4cos(θ)^3 - 4cos(θ)

But it should be sin(θ) since I'm applying this formula:

40d6f1331ce8aba3f36bc39d3a8fae78.png


and the solution for 1,1 is Sqrt(3/8π) e^((+/-)iφ) * sin(θ)
I get how the part in italics is derived, but not how the part in bold has been derived from the associated legendre polynomial..
 
I think you've made an error in your calculation. If we plug in ##\ell = 1## and ##m=1##, we have $$P^{1}_{1}={(-1)^1 \over 2 \cdot 1!} (1-x^2)^{1/2} \cdot {d^2 \over dx^2}(x^2-1)$$
Do you have that much? It should be easy to simplify that, then plug in ## x=\cos{\theta}##.
 
Great I have it now. -(1-cos()^2)^(1/2), which is equal to sin(θ).

Right I have it now, like you said I made a small error in not applying l+m, but instead just l and some errors on other places as well.

Thanks for the quick reply! :)
 

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