Radial Eigenfunction; Differential Equation

In summary: I looked it up and the problem statement is "Given a particle in one dimension subject to a potential energy, find the position and momentum of the particle at a later time.". I think that's what they want, but they might want more specific information.I think they want you to find the eigenvalues and eigenvectors of the radial eigenfunction.
  • #1
Paradox101
47
1

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 Schrodinger 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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  • #2
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##.
 
  • #3
well, i had to look at the soln on the back of the book. Never mind, i got it anyway.
 
  • #4
Was it something like "differentiate u twice and verify that it satisfies the equation" or was it different ?
 
  • #5
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.
 

1. What is a radial eigenfunction?

A radial eigenfunction is a type of eigenfunction that is dependent only on the distance from the center of a system, rather than on the direction. It is commonly used in the study of differential equations, particularly in problems involving spherical or cylindrical symmetry.

2. How is a radial eigenfunction related to a differential equation?

A radial eigenfunction is a solution to a particular type of differential equation known as a radial differential equation. These equations are used to describe physical systems with spherical or cylindrical symmetry, and the radial eigenfunction represents the spatial dependence of the system.

3. What is the importance of solving for radial eigenfunctions in physics?

Radial eigenfunctions are crucial in understanding the behavior of physical systems with spherical or cylindrical symmetry. They allow us to accurately describe and predict phenomena such as atomic orbitals, electromagnetic fields, and quantum mechanical systems.

4. How are radial eigenfunctions calculated?

The calculation of radial eigenfunctions involves solving the corresponding radial differential equation, which can be done using various mathematical techniques such as separation of variables, power series, or numerical methods. The specific method used will depend on the complexity of the system and the desired level of accuracy.

5. Can radial eigenfunctions be used to solve problems in other fields besides physics?

Yes, radial eigenfunctions have applications in various fields such as mathematics, engineering, and chemistry. They are particularly useful in problems involving spherical or cylindrical symmetry, but can also be applied to more general systems through techniques such as coordinate transformations.

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