Solving ψ'' - y²ψ = 0 for the harmonic oscillator

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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[itex]^{2}[/itex])ψ=0

I am letting y[itex]\rightarrow[/itex] [itex]\infty[/itex] to get...

ψ''- y[itex]^{2}[/itex]ψ=0

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

ψ= Ay[itex]^{m}[/itex]e[itex]^{\pm y^{2}/2}[/itex]

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
 
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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  • Handwritten-style worked notes solving the ODE d²ψ/dy² − y²ψ = 0 via modified Bessel functions I and K of order 1/4 and asymptotic expansions, ending with a boxed asymptotic form of ψ(y).
    EDO 1.JPG
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