Quantum Harmonic Oscillator Differential Equation help

cybla
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Hi, so i am looking at the quantization of the harmonic oscillator and i have the following equation...

ψ''+ (2ε-y^{2})ψ=0

I am letting y\rightarrow \infty to get...

ψ''- y^{2}ψ=0

It says the solution to this equation in the same limit is...

ψ= Ay^{m}e^{\pm y^{2}/2}

The positive possibility in the exponential is ignored since it is not in the physical Hilbert space. My question is how did they solve this differential equation? I have read a couple websites and it says that you just have to "guess" it... however, is there a logical way to why you would guess this? Thank you
 
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The solutions of this EDO are known in terms of Modified Bessel functions or alternately in terms of Parabolic Cylinder functions (in attachment)
 

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    EDO 1.JPG
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For the ODE just use the Frobenius method. Series expansion.
 
Okay i understand, thank you very much
 
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