Radial Eigenfunction; Differential Equation

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Homework Help Overview

The discussion revolves around demonstrating that the radial eigenfunction \( u_{n,r,l} \) satisfies a specific differential equation related to the radial Schrödinger equation in quantum mechanics. The context involves concepts of angular momentum and effective potential in a quantum system.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need to differentiate the radial eigenfunction twice and compare it to the effective potential. There are attempts to understand the relationship between the radial function and the differential equation, with some participants expressing uncertainty about how to begin the proof.

Discussion Status

The discussion is ongoing, with some participants seeking clarification on the problem statement and relevant equations. There is a suggestion to post detailed work if further difficulties arise, indicating a collaborative effort to explore the problem. However, no consensus has been reached on the approach to take.

Contextual Notes

Some participants note discrepancies in the resources they are using, mentioning different books and expressions for the radial eigenfunction. This suggests potential confusion stemming from varying notations or formulations in different texts.

Paradox101
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Homework Statement


Show that the radial eigenfunction unr,l is a solution of the differential equation:
ħ2/2me×d2unr,l/dr2+[l(l+1)ħ2/2mer2 - e2/4πε0r]unr,l=Enr,lunr,l

Homework Equations


The radial function is R(r)=u(r)/r, so that the expression on the RHS is E×u.

The Attempt at a Solution


I know that this equation is the radial Schrödinger equation, and that the particle with angular momentum L behaves like a particle in one-dimensional effective potential.But, to prove it, i don't know where to start.
I tried comparing this potential with the analogous effective potential and set the first term, l(l+1)ħ2/2mr2, but with no luck. Any ideas, please?
 
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I had to look it up in Griffiths (https://archive.org/download/IntroductionToQuantumMechanics_718/6804026-Physics-Introduction-to-Quantum-Mechanics-Ph-1995.pdf) and the problem statement seems OK. I do expect, either in the problem statement, or in the relevant equations, an expression for the radial eigenfunction ##u(n, r, l)##. Because the exercise wants you to show that it's a solution.

Your relevant equation R = u/r isn't of interrest, I'm afraid. They want you to differentiate u twice.

Embark on that task and post the work (in reasonable detail) if you still get stuck.

You may want to adopt the notation (4.55) in the link to avoid excessive amounts of ##\hbar\over 2m## etc. -- but then you need your u also in terms of ##\rho##.
 
well, i had to look at the soln on the back of the book. Never mind, i got it anyway.
 
Was it something like "differentiate u twice and verify that it satisfies the equation" or was it different ?
 
nope, it was different. The book u r referring to, is the one i have already read. This is a different book, and a quite old one too---- It doesn't have a proper cover.
 

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