Eigenenergies of finite square well

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Discussion Overview

The discussion revolves around the analytic form of the eigenenergies of a one-dimensional finite square well potential, including inquiries about resources and methods for finding these eigenenergies. The scope includes theoretical aspects and mathematical reasoning related to quantum mechanics.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant inquires about websites that provide the analytic form of the eigenenergy for a finite square well potential.
  • Another participant suggests that standard quantum mechanics textbooks, such as Davydov, typically cover this topic and implies that the information may be readily available there.
  • A different participant asserts that there is no explicit analytic expression for the energy eigenvalues of a finite square well and explains that solving the problem requires addressing a transcendental equation for both odd and even parity eigenfunctions.
  • This participant also mentions that numeric solutions can be obtained to any desired precision and suggests searching online for resources related to the finite square well.
  • Another participant shares their experience working on a variational method problem, stating they are using a Gaussian trial function to demonstrate that a finite square well should have at least one bound state, and seeks validation for their approach.

Areas of Agreement / Disagreement

Participants express differing views on the availability of analytic expressions for eigenenergies, with some asserting that they do not exist in a straightforward form while others reference textbooks that may contain relevant information. The discussion remains unresolved regarding the specifics of the analytic forms and the methods to obtain them.

Contextual Notes

There is an indication of missing assumptions regarding the definitions of terms used in the discussion, particularly concerning the nature of the eigenenergies and the conditions under which they are derived. The reliance on transcendental equations and numerical solutions introduces additional complexity that is not fully explored.

secret2
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Is there any website where I can find the analytic form of the eigenenergy of a 1-D finite square well potential?
 
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I'm sure there is,but don't u have a textbook...?IIRC,there's a nice presentation of this problem in Davydov.

Any QM textbook ought to have finite square well...

Daniel.
 
secret2 said:
Is there any website where I can find the analytic form of the eigenenergy of a 1-D finite square well potential?

There's no explicit analytic expression for the energy eigenvalues of a finite square well. To get them, you have to solve a transcendental equation (two of them actually, one for odd-parity eigenfunctions, one for even-parity). This gives you numeric solutions to whatever precision you need.

Unless of course someone has defined some kind of special function to fill the fill, but I've never heard of any such thing.

Do a Google search for "finite square well" (with the quote marks) and you'll find plenty of Web sites. Some of them probably include the transcendental equations in question.
 
In fact, I am working on a variational method problem. I am asked to prove that any finite square should have at least one bound state. So I plug in a Gaussian trial function to the square well potential. The variational method give neatly V (which is the "depth" of the well). Just want to check if this makes sense.
 

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