Calculating Base State for the H Atom using Inverse Fourier Transform

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Discussion Overview

The discussion revolves around the calculation of the base state wave function for the hydrogen atom using the inverse Fourier transform. Participants explore the mathematical steps involved in the integration process, addressing both the formulation and the challenges encountered in the calculations.

Discussion Character

  • Mathematical reasoning
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant presents the inverse Fourier transform formula and the specific form of the momentum space wave function, \(\Psi(p)\).
  • Another participant attempts to simplify the integral by changing variables and expresses the integral in terms of cosine, indicating a potential path to the solution.
  • A third participant shares the result obtained from Mathematica, which appears complex and involves special functions, suggesting the difficulty of the integral.
  • A later reply identifies an error in the previous calculations, specifically regarding the use of sine instead of cosine, and suggests that correcting this will lead to the expected base state for the hydrogen atom.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct approach or the final result, as there are differing interpretations of the integral and its components. The discussion remains unresolved regarding the exact form of the base state wave function.

Contextual Notes

Participants express uncertainty about the integration steps and the implications of their mathematical manipulations. There are unresolved issues related to the correctness of the transformations and the handling of complex exponential terms.

Gatts
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Inverse Fourier Transform

I have to calculate (don't take in account the units, obviously the're extrange)

[tex] \phi (r)=\frac{1}{(2\pi\hbar)^{3/2}}\int d^{3}p\hspace{7mm}{e^{i\frac{-p\cdot r}{\hbar}}\Psi(p)}[/tex]

[tex] \Psi(p)=\frac{B}{(1+\frac{p^2}{m^2})^2}[/tex]
I know that

[tex] d^{3}p=p^{2}Sin(\theta)dpd\theta d\phi[/tex]

So i do

[tex] \phi (r)=\frac{1}{(2\pi\hbar)^{3/2}} \int p^{2}Sin(\theta)dpd\theta d\phi\hspace{7mm}{e^{i\frac{-p\cdot r Cos(\theta)}{\hbar}}\frac{B}{(1+\frac{p^2}{m^2})^2}<br /> }[/tex]

but i use the change of variables

[tex] u=Cos(\theta);du=-Sin(\theta)d\theta[/tex]

And the the integral take the form


[tex] \phi (r)=\frac{2\pi}{(2\pi\hbar)^{3/2}} \int_{1}^{-1}\int_{0}^{\infty}p^{2}dpdu \hspace{7mm}{e^{i\frac{-p\cdot r u}{\hbar}}\frac{B}{(1+\frac{p^2}{m^2})^2}<br /> }[/tex]
 
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Integrating

[tex]\phi (r)=\frac{2\pi} {(2\pi\hbar)^{3/2}} B \int_{0}^{\infty}pdp \hspace{7mm} \frac{\left(e^{i\frac{p r}{\hbar}}-e^{i\frac{p r}{\hbar}} \right){\frac{i p r}{hbar}\frac{1}{(1+\frac{p^2}{m^2})^2}[/tex]

Multipliying for [tex]\frac{2}{2}[/tex] to form a cosine, so it is

[tex] \phi (r)=\frac{2\pi} {(2\pi\hbar)^{3/2}}\frac{2 B\hbar}{i r} \int_{0}^{\infty}pdp \hspace{7mm} Cos(\frac{p r}{\hbar})\frac{1}{(1+\frac{p^2}{m^2})^2}<br /> }[/tex]
 
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Bu the las integral, it is just a nightmare... the results froma Mathetmatica 6.1 is:

[tex]\frac{1}{2} m^2 \sqrt{\pi } MeigerG[{{0},{}},{{0,1},{\frac{1}{2}},\frac{m^2 r^2}{4\hbar^2}][/tex]

i as expecting the base level for the H atom [tex]\phi (r)[/tex], so if somebody could help me please...
 
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Na i found my error was a Sine not a cosine what I get afeter I do the first integral in du, I don't know why the page don't uptadete what I've write, but that was the error, mulltiply bi 2i/2i and you will get the base state for the H atom, THE ANSWER...
first part of the trip...
 

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